Don't let this happen to you.....
 

Had a tire fail just south of Jasper after a full day of fishing. The lock on the spare would not open and the threads on the bracket gaulded up. Lucky the lock was a long one so I put the tire tool through it and broke it.

that's why I make a point once a year to push some grease into the openings on the locks on my trailer and work in in real good and I rub grease on the threads for the tires as well as the spare.

the lock on the receiver is mostly blocked by your truck from getting water blasted by rainy weather but the spare tire one can get water forced into it as you drive in bad weather so that is the one I most worry about.

I hate them twisty things so I get the holder with regular lug nuts on it and then use a chain to go around the frame and through the rim to lock it.

Put a dab of nickel based Anti-Sieze over the lock key and shackle openings and work your key in and out/ open and close several times....then clean your hands and key well because it is messy at first. Wipe off any excess on the lock. You will NEVER have any problems with your lock freezing. Also putting anti-seize on your lug-nuts and other corrosion sensitive threaded parts is advisable. Make sure it is nickel based as it is designed for high-temps/ corrosion prone threaded parts.

I try and hit all the sensitive spots with some water resistant lube several times a year. We also rinse everything: boat, trailer, motor, locks, hardware after each use in salt or brackish water.