If he let's you watch, you might see him "impression" a key for you.
Amazing what they can do with a small pair of vice-grips, magnifying loupe and a file.
Or, for now, get it out, if yours is what I think it is, depress the retainer, slide the lock cylinder out, pull ALL the tumblers and bits, put them in a zip-lock, and you can use ANY key to open it!
Done that on old cars with lock assemblies that are currently manufactured of "un-obtainium" and so worn out you can'y get the tumblers to work.
Nobody knows but you!