title: Codeigniter session query in mysql slow query
body: <p>I'm maintaining a heavy traffic web app providing RESTFul API using codeigniter and mysql.
  After turning mysql slow query log with 1 second long query time following query is login repeatedly with execution time of 100+ seconds.</p>
  <pre><code>SELECT GET_LOCK('fhn1enbb1u9hgu4m1tq32fbsds4c8ohj', 300) AS ci_session_lock;
  </code></pre>
  <p>It seems something with codeigniter configuration please help.</p>
  <h1>Sample slow query log:</h1>
  <pre><code>SET timestamp=1554912062;
  SELECT GET_LOCK('fhn1enbb1u9hgu4m1tq32fbsds4c8ohj', 300) AS ci_session_lock;
  Time: 2019-04-10T16:01:02.640796Z
  Query_time: 99.819745  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0
  
  SET timestamp=1554912062;
  SELECT GET_LOCK('taff1quqs4gv2g33740t41cdplnpkof8', 300) AS ci_session_lock;
  Time: 2019-04-10T16:01:03.082128Z
  Query_time: 94.859307  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0
  
  SET timestamp=1554912061;
  SELECT GET_LOCK('fhn1enbb1u9hgu4m1tq32fbsds4c8ohj', 300) AS ci_session_lock;
  Time: 2019-04-10T16:01:01.979967Z
  Query_time: 106.766586  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0
  </code></pre>