The invention relates to an electrically operable locking device for locking a gate. The electrical lock has a frame for mounting the locking device to the gate, and a housing slidably movable with respect to the frame between an upper position and a lower position and comprising a drop bolt arranged to move between an extended drop bolt position and an retracted drop bolt position and a mechanical locking mechanism arranged to lock and unlock the housing to the frame and comprising a key-operated cylinder lock to unlock the housing to the frame. The gate is locked if said housing is in the lower position and said drop bolt is in the extended position. The locking device further has a resilient element positioned between the frame and the housing and arranged to lift the housing relative to the frame when the housing is unlocked from the frame by operation of the key-operated cylinder lock.