Delayed updates (no replies)

Hello,

Sometimes, when the server is busy and I do UPDATE or INSERT in an InnoDB table using a function like UNIX_TIMESTAMP() as one of the values, there is a delay between the calculation of the value and the real update of the table.
Another server-side script is using these values to retrieve the recently updated/inserted rows, but when a such delay appears, it creates problems.
Is there a way to force the calculation of UNIX_TIMESTAMP() just before the real update ?

Thanks,
Olivier