I know that there was one up at the Lock Museum of America every Oct.
The Lock Museum of America
This listing is a few years old but I would think that if you were to contact them they can tell you if it is still going to be held.
As for “Locksmith” shows there are always keys to be had but nothing in the antique section to speak of. I just network with other locksmiths if I have looking for a OEM keyblank or old key blank.