It looks like a J-38 style key.
Probably worth 20-30 depending on condition. There were several manufacturers as well, and that can also make a good swing in the price as well....in either direction.
Collectors like Lionell keys of this design. (The train folks made a J-38, which is probably the most popular J-38 key out there.....closely followed by the USN keys.)
I like old keys..... they have a sweeter feel under your hand when you're sending, and no need for electronic keyers like the modern paddles.
PM me if you want with any markings or numbers, and I will try to find some more info for you. (or... if you want to get rid of it, maybe I could make an offer.)
Pawaide