Very rare fine (expensive) steel lock and key (maybe Persian). Some geometric ornamentations and tiny remainders of brass or gold inlays. Probably Persian Safavid. This is probably the predecessor of the Omani Mandoos lock or an Omani door lock.
Sir Richard Burton who lived in Zanzibar for some time wrote in the book Zanzibar City Island and Coast 1872 "the bigger the gateway, the heavier the padlock and the huger the iron studs which nail the door of heavy timber the greater is the owner´s dignity"