It reminds me of the keys used in many common 1930's--1950's locking gas caps, including Ford ones supplied as accessories in the flathead era.
I had a number of nice but keyless V8 ones, and went hunting. What I found was a simple picking key for those, really just a flat piece thin enough to bypass the center groove with a couple of bumps on each edge and costing very little. It was marketed as a gas station tool specifically for coping with gas caps.
Just pushing it in and wiggling it a bit unlocked every such lock I owned, many of them almost as easily as the proper key could have. Generally, if you can turn a lock cylinder the big problem is over, as you can then work its latching system and get it out to have a key made.