Is there a way I can "lubricate" the locks? on 1992 Chevrolet 1500 Pickup

I can still manually lock the doors from inside and, just barely, lock them using a key. I am afraid of breaking the key off while doing this. Any helps? Will I injure anything by squirting silicone lubricant into the lock mechanism?

Asked by for the 1992 Chevrolet 1500 Pickup
it will help