Good buy :) as for the lock if sounds as if the tumblers are seized in the barrel, if you are not in a hurry just strip the lock and remove, clean and refit one tumbler at a time.
Alternatively if you are sure the car has not had a lock change at any time you can order a new door lock cut to the chassis number from any Lexus dealer ;) only £48.52 + vat retail.
Andy