While I am by no means an expert or extremely knowledgeable on Spanish coins, it appears to me to be a genuine 8 Reale coin minted during the reign of Carolus III (King Charles III) of Spain. Not sure when they began minting coins with his' image on the Obverse (the Reverse is showing on your' coin) but he reigned from 1759 to 1788.
If you are wondering about the wood lined Silver box, then I believe that is/was a somewhat personalized Cigar Box and has probably held some very expensive Cigars during it's use.
Frank