I have a 93 FD and the drivers door lock will not unlock with the key. Seems very tight and if I twist the key anymore it will feel like it'll break. I have to crawl through the passenger side to unlock the drivers side which sucks. Any suggestions on what to check for first?

 

Have a look in the keyhole, a common problem is that the white plastic cover inside breaks and fragments get lodged onto the keyway. Believe it or not once apon a time these keyways apparently lit up and think this plastic part is part of that. If it appears clear just remove the lock cover and have a look at the mechanism

 

That's interesting, I'll check it out in the morning. Thanks!

 

The problem is likely not in the lock cylinder but in the numerous rods that connect to it.
This is a very common issue with these cars...searching will yield a lot of results. But it is pretty easy to lubricate the rods, etc...just take off the little triangular cover inside the car, remove the two 10mm fasteners; this allows the outside handle to be pulled away from the car a good distance. You'll see all the little rods, spray them liberally with your favorite lube.
IF on the other hand the key just doesn't want to turn hardly at all in the lock cylinder, that too is a fairly easy fix if you are even halfway mechanically apt.
Disassemble the lock cylinder from the handle. If it still has difficulty turning, it needs servicing. If not, the problem is in other parts of the door lock. If so, take it to a large open area like a kitchen table, lay out a newspaper and start taking the cylinder apart. Don't be intimidated, it looks far worse than it is. You can see if there is any debris, as OG BBF noted whilst you do this.
Clean and lube all the tumblers and springs. Take careful note of the order/identification number on the tumblers and be sure to put them back in the same manner. Now you'll also understand how keys/locks work.
Oh, and this is a good time to fix the door lock light...you'll see it tucked into a rubber grommet with two wires coming out of it. Find a suitable 'grain of wheat' replacement bulb at any electronic supply store like Radio Shack.
Put it all back together...take your time...and be ready to enjoy the joys of a properly operating (and illuminated!) door lock.

 

Man, good info here. Really appreciate it!