@Huma0 I had a similar problem, old locks without keys, and found a locksmith here in Zagreb who came, took out the entire lock, cleaned it, made new keys, and installed it back on the door. So yes, it is possible.
He said that old locks are of great quality and last more than 100 years while new ones break easily.
This locksmith is the only one who also makes BMB keys in Zagreb, and I call him whenever I have some more complicated problem with the locks.