Time-based trigger

We have a table, which has items that can be put on hold of 5 minutes (this is for an online store) once they are placed into a cart.  What we need is for this hold to automatically expire after 5 minutes.  Right now, we put a time stamp into the row (called hold_until) at 5 minutes into the future, and select items where hold_until is less then now().

Would it be possible to change this to using a boolean that is set to true when item is put on hold, and have something like a time-based trigger automatically update the held boolean to false after 5 minutes pass.

Thanks,