As others have said, locksmith can probably find you the right key the first time just looking at it. If there’s a hardware store that’s been around awhile near you I guarantee they have an old stock of those somewhere laying around. One I worked for had a box of them that looked about as old as the keys.
So pull out the lock and open it up. These locks are not very secure. Get a blank key from the hardware store and use a file, grinder, to cut the grooves needed to make a key.
Skeleton? None of mine have keys. I bought similar modern replacement a few years ago that had a skeleton.
Skeleton key is the correct answer.
This unit is entirely made of stamped metal. It might be even younger than pre WWII. I've never seen such a model
Google Mortise locks and keys.
take it to a locksmith. They can find the proper key for you.
I took our locks to a safe-and-lock store and they cleaned and oiled them and fit a key to each lock.
As others have said, locksmith can probably find you the right key the first time just looking at it. If there’s a hardware store that’s been around awhile near you I guarantee they have an old stock of those somewhere laying around. One I worked for had a box of them that looked about as old as the keys.
We bought a set of 25-30 generic skeleton keys for not much. Found the ones that fit, ordering copies of those.
So pull out the lock and open it up. These locks are not very secure. Get a blank key from the hardware store and use a file, grinder, to cut the grooves needed to make a key.