Besides my occasionally used auto door locks, I have the same problem with seldom used home door locks.

You may be able to get them to turn with regular lubricating oil. If you use a penetrating oil first, once loose, give them a shot of lubricating oil. I've been using PB50 lubricant, same company that makes PB Blaster penetrant.
BTW, WD40 is not a good penetrant or lubricant, use something better for both needs.