Does your cron program run continuously? what database are you using? If you are using a database that supports mvcc (Oracle, Postgres, MySQL with InnoDB tables, possibly others), your first select (of any kind, not just this query) logically freezes the state of the database, and you will not see any updates until you start a new transaction (which would happen by starting the cron job again, but might be done manually).
Lookup ACID trait of databases - you might be seeing the I=Isolated property in action.
