The invention concerns a closing device with selective locking for closing a frame (2), said device comprises a lid (1), a lock (13, 15), and a key (3) including a socket (7) and an arm (8), the lid having an opening (4) for the key to accede to the lock, the lock (13, 15) comprising a lock-bolt (15) co-operating with a lock-bolt keeper (27), and the key (3) selectively adopting a locking position which said key may freely adopt or be released from, and wherein the lock-bolt (15) is blocked in the lock-bolt keeper (27), and a position for which the key (3) is locked in the opening (4) and for which the lock-bolt (15) is released from the lock-bolt keeper (27). The invention is characterised in that the arm (8) and the socket (7) are substantially perpendicular to each other, and the arm (8) is substantially perpendicular to the lid (1) for the position unlocking the key.