title: Mysql select query between dates takes more execution time
body: <p>In my test table there are 1 million rows, column id is auto generated number from 1 to one million and id column is unique index, timestore column storing insertion time, when execute select query between id  range Ex:</p>
  
  <pre><code>select * from test where id &gt; 345673 and id &lt; 453267
  </code></pre>
  
  <p>Execution time - 0.379s</p>
  
  <p>if execute select query between two dates</p>
  
  <pre><code>select * from test where timestore between '2014-12-28 16:59:50' and '2014-12-28 17:1:50'
  </code></pre>
  
  <p>Execution time - 1.478s</p>
  
  <p>Why second query takes more than first ?</p>