This happens to alot of locks. Even the ones on my Boaphiles will rust. Normally, I will occassionally take the lock apart and scrub it with a steel wire brush and either gun oil or WD-40. Then I will soak it in Isopropyl alcohol to remove the oil before putting it back together.
I used a version of this tank mod to convert a 75 gallon aquarium into a display cage for my IJ Carpet Python. I wasn't real comfortable about laying it on it's side because of the size and weight of the 1/4" glass, so I just made the locking plexiglass lids to fit the top.