In short

Keycard Grand Hotel is a keycard for the building “Grand Hotel” in Sunny Beach. It opens: locked room. Behind the door: 2 large safes, 2 cabinets, 1 computer · Powder, Alcohol, Cash. The key fits only this place.

KeyBuildingDistrictOpens
Keycard Grand HotelGrand HotelSunny BeachLocked room

Where it is

The building is on the interactive map. All keys, doors and safes of the city: Locked doors, Safes and containers, the key guide.

The game data does not list where this key drops or is sold, so we do not guess.