title: Adding minutes to timestamp and selecting the records which are not expired
body: <p>Schema for table invoice</p>
  <pre><code>id (int)    
  creation_timestamp (big int)    
  username (varchar(100))
  </code></pre>
  <p>Query</p>
  <pre><code> SELECT 
      *
  FROM
      `invoice`
  WHERE
      `creation_timestamp` BETWEEN UNIX_TIMESTAMP(DATE_ADD(creation_timestamp,
                  INTERVAL 15 MINUTE)) AND creation_timestamp
  </code></pre>
  <p>I am trying to select the invoice which are not expired where expiration should be 15 minutes from creation timestamp.</p>
  <p>creation_time stamp is the unix timestamp when the invoice is created. I am adding 15 minutes to creation_timestamp because I want to make 15 minutes as expiry of the invoice but its not working.</p>