On many of the older 40s/50s typewriters, the same key will work on almost everything. If you search online there are a few people who have posted a 3D printable key that you can download and may be able to print at your local library. I'm guessing based on the limited photo, yours is an early 40s Smith-Corona.

I've tried a few local locksmiths who don't seem to carry these keys anymore.

I've got a late 40s Smith-Corona latch that occasionally self-locks and for ages I used a bent paperclip in the rough shape of the old keys to easily pick the lock with just 10 seconds of jiggling around inside. Roughly a 2 mm straight section of paperclip with a 1mm "T" section that sticks out (even just on one side) about 4-5mm and then continues straight ought to work if you're in a jam.

The level of security these keys/locks provide is minimal at best.

If you go the online route to buy a key, they can be quite expensive, so if you're a collector, just wait for a machine that comes with one and you'll have another typewriter for "free" in the deal.

reply to u/Succu6us66 at https://old.reddit.com/r/typewriters/comments/1eqk6rd/typewriter_lock/