MySQL IF without else
SELECT * FROM callback LEFT JOIN agent ON callback.agent_ID=agent.agent_ID
LEFT JOIN contact ON callback.contact_ID=contact.contact_ID WHERE callback.agent_ID =118
AND DATE(callback.cb_dt) =curdate()
and Hour(time(callback.cb_dt)) <= Hour(time(UTC_TIMESTAMP()))
and
(if(Hour(time(callback.cb_dt)) = Hour(time(UTC_TIMESTAMP())),
minute(time(callback.cb_dt)) < minute(time(UTC_TIMESTAMP())) and
cb_IsDeleted=0 ,cb_IsDeleted=0))
and callback.isCalled=0;