Countersink a couple of hatch latches.

You'll find some with a handle that lays flat in a dedicated groove until you
want to open the hatch. To use the latch, you lift up on the handle and turn.
When you return the cold storage lid you twist the handle 90 degrees and dog it
down snugly-
then you can lay the handle into the groove and it will leave a smooth work
surface.

Downside: the recessed area will be a nuisance to keep clear of crumbs etc in a
galley environment.