ok, I have some info on the lock now. That is what is known as a “screw key” type lock, and yes it is pre-civil war. Finding a key for it would be extremely difficult but would add a ton of value.
You could, however, have a locksmith with the right mind make you a replacement key. This key itself would be worthless but would add value to the lock itself since it could be “worked” by a collector. You have a very nice lock there, but I have no idea what it would sell for.
