What exactly is INTERVAL 1 HOUR checking?
Since the WHERE clause says NOW(), the expression STAMPFOO &gt; NOW() - INTERVAL 1 HOUR makes this a dynamic query. It will return all records whose timestamp is greater than one hour ago, down to the very second.

If you run this at 2017-02-02 12:15:27, your query will return all FOO values  from 2017-02-02 11:15:27.