HEAP table

I have a query that I would have liked to cache, but as it uses UNIX_TIMESTAMP and has a user variable in it, where cacheing won't work, I looked around for another way to do it (it is used to create a smallish < 50 records table on each web page, so any speed increase is worthwhile). I decided to go for the creation of a HEAP table, so that anyone accessing the site would automatically access it. The existence of the table is tested for before initial creation by running a select against it and testing the $result variable. This works, as far as it goes, but it will require occasional updating. And that's where I've come unstuck. How can I test for the time/date of the HEAP table's creation? If I can find that, then I can set a seconds value past which it should be dropped and recreated. Any ideas? Using MySQL 5.0.13, php 4.3.2 (on Windows XP), Apache 1.3 whatever. This also has to work on the website proper, using 5.0.13/4.3.1 and IIS5. Terry Riley