Abstract: A locking mechanism of the key lock type or code lock type for installation in a door of a vault or safe, includes at least one locking bolt for movement between a locking position in which a door is locked and an unlocking position in which the door is released for opening, an electromechanical actuator connected to the locking bolt for moving the locking bolt between the locking position and the unlocking position, a time delay circuit so interacting with the actuator as to delay operation of the actuator for a specified time period, with the time delay circuit being so positioned as to be inaccessible upon closed door and including an activation input for cooperation with a switch accessible from outside such that the time delay circuit is activated.