Driver and passenger door won't unlock with key

Hey guys, I just bought my 91 super custom limited a couple weeks ago. The biggest issue I'm having now is that the driver and passenger doors won't unlock with my key. But the rear sliding door locks and unlocks just fine. Any help would be greatly appreciated!

Does the central locking work if you press the 'lock/unlock' button on the drivers door?

It doesn't have an actual button but if I lock or unlock the driver door with the lock above the handle, it unlocks and locks all doors

Sounds like the central locking is OK then.
So could it be the external key barrel switches only?

Maybe try WD40 first in the keyholes, if not you may need to take the door trims off and have a look.

Alright thanks I'll try that