Check your key with the glove box and rear hatch, if it fits there then the door was replaced and the lock never updated.
Considering that this is a salvage car, I expect that the ignition lock came from a donor car if the key doesn't fit the glove box.

Or, it could be that the door lock is jammed with rust. It can be removed and brought to a locksmith to match your key or repaired.

There is only one key per Volvo.