Twist lock receptacles exist in the US, I mostly see them used for server racks.
NEMA L6-30R is a locking 208/240v 30 amp receptacle. L means locking, the 6 means two hots and a ground at 208v or 240v, (240v for 240v split phase and 208v for 208v 3p wye) 30 is amp max amps, R means receptacle.