Escape room creators know that if they want a lock that looks and feels old, there are a few options for faux antique locks.
However, there are other options if you’re willing and able to do some physical construction. In this video, Adam Savage (of MythBusters fame) shows us how to take an antique key and build a functional and sturdy lock around it.

If lock construction feels like far too much effort, Savage also does some beautiful finishing and weathering on his build.
There is a remarkable amount of technique on display here. I think that there is something for every maker.
My one big note is that if you’re going to do this, please build around a key that you can get a few copies of… or take the measurements so that you can machine one if you need it.