Lock picking
Oh,i agree. The design of the keyway dates it to a point tho. If it was old old, it would have the key in the front.
That is a cylinder style, "modern" key type and i dont think they had great anti pic tech figured out back then.
But no matter what, it is super cool.
I bet if you got it open, then drove out the hinge pin, the entire bottom plate falls out with the cylinder.
Just my thoughts tho.
Edit- now i see the two lower pins. But i bet when locked it may not dissemble as a design.