mysql - My Insert queries is blocking my select queries. CPU usage of server goes upto 100% for postgres -

i using select , insert queries on table. cpu usage goes upto 100% postgres. how can optimize it

table structure , queries follow

create table ad_request (     request_id bigserial not null,     client_id integer default 0,     ad_type integer default 0,     ad_unit integer default 0,     host_url character varying(150) default null::character varying,     ip_address character varying(20) default null::character varying,     referer character varying(350) default null::character varying,     platform character varying(20) default null::character varying,     browser character varying(20) default null::character varying,     served_campaign_id bigint default 0,     status character(1) not null default 'n'::bpchar,     created_time timestamp without time zone not null default now(),     constraint ad_request_pkey primary key (request_id) ) (     oids=false ); alter table ad_request     owner postgres;   select served_campaign_id ad_request client_id=1 , ad_type=1 , ad_unit=1 , ip_address='192.168.1.1' , created_time > current_timestamp - interval '24 hour';  insert ad_request(client_id,ad_type,ad_unit,host_url,ip_address,referer,platform,browser,served_campaign_id) values(?,?,?,?,?,?,?,?,?); 

output of explain analyze seelct query is

 seq scan on ad_request  (cost=0.00..52629.15 rows=1 width=8) (actual time=245.512..245.512 rows=0 loops=1)  filter: ((client_id = 1) , (ad_type = 1) , (ad_unit = 1) ,     ((ip_address)::text = '192.168.1.1'::text) , (created_time > (now() -   '24:00:00'::interval)))  total runtime: 245.544 ms  (3 rows) 

and output of insert query is

 result  (cost=0.00..0.02 rows=1 width=0) (actual time=0.092..0.094 rows=1 loops=1)  total runtime: 0.198 ms  (2 rows) 

and ouput of select * pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid;

datid | datname | procpid | usesysid | usename  |                                     current_query                                   | waiting |          xact_start    |          query_start          |         backend_start         |   client_addr | client_port |  locktype  | database | relation | page | tuple |   virtualxid | tran   sactionid | classid | objid | objsubid | virtualtransaction | pid  |       mode       | granted    -------+---------+---------+----------+----------+----------------------- ------------------------------------------------------------+---------+---------  ---------------    -------+-------------------------------+-------------------------------+-------------+-------------+------------+----------+----------+------+-------+------------+-----   ----------+---------+-------+----------+--------------------+------+-----------------+---------    20916 | adtag   |    1307 |       10 | postgres | select *  pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |  2015-04-01 06:00:27.700     012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |             |          -1 | relation   |    20916 |    10969 |      |       |            |       |         |       |          | 1/1272802          | 1307 | accesssharelock | t     20916 | adtag   |    1307 |       10 | postgres | select * pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |   2015-04-01 06:00:27.700    012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |             |          -1 | relation   |        0 |     1262 |      |       |            |       |         |       |          | 1/1272802          | 1307 |   accesssharelock | t     20916 | adtag   |    1307 |       10 | postgres | select *  pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |    2015-04-01 06:00:27.700    012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |             |          -1 | relation   |        0 |     1260 |      |       |            |       |         |       |          | 1/1272802          | 1307 | accesssharelock | t    20916 | adtag   |    1307 |       10 | postgres | select * pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |    2015-04-01 06:00:27.700    012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |             |          -1 | relation   |        0 |     2671 |      |       |            |       |         |       |          | 1/1272802          | 1307 | accesssharelock | t     20916 | adtag   |    1307 |       10 | postgres | select * pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |  2015-04-01 06:00:27.700     012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |             |          -1 | relation   |        0 |     2676 |      |       |            |       |         |       |          | 1/1272802          | 1307 | accesssharelock | t   20916 | adtag   |    1307 |       10 | postgres | select * pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |  2015-04-01 06:00:27.700   012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |             |          -1 | virtualxid |          |          |      |       | 1/1272802  |       |         |       |          | 1/1272802          | 1307 |  exclusivelock   | t    20916 | adtag   |    1307 |       10 | postgres | select *  pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |    2015-04-01 06:00:27.700   012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |              |          -1 | relation   |    20916 |    11042 |      |       |            |       |         |       |          | 1/1272802          | 1307 |  accesssharelock | t    20916 | adtag   |    1307 |       10 | postgres | select *  pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |  2015-04-01 06:00:27.700  012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |              |          -1 | relation   |        0 |     2672 |      |       |            |       |         |       |          | 1/1272802          | 1307 |  accesssharelock | t    20916 | adtag   |    1307 |       10 | postgres | select *  pg_stat_activity pga inner join pg_locks pl on pga.procpid=pl.pid ; | f       |  2015-04-01 06:00:27.700    012+00 | 2015-04-01 06:00:27.700012+00 | 2015-04-01 04:04:49.810039+00 |              |          -1 | relation   |        0 |     2677 |      |       |            |       |         |       |          | 1/1272802          | 1307 |  accesssharelock | t   (9 rows)