A lock assembly has a lock body and a flexible key. The lock body includes at least two plug pieces having confronting faces with longitudinal curved grooves. The plug pieces cooperatively form a cylindrical plug. The curved grooves are complementary so as to form a longitudinal curved keyway with a cross-section that is shaped to have an upright first portion and a cross-wise second portion. A first set of tumbler members is provided on the cylindrical plug and extends in the direction of the upright first portion. A second set of tumbler members is provided on the cylindrical plug and extends in the direction of the cross-wise second portion. The flexible key is adapted to be received in the curved keyway and is useful for actuating the tumbler members. The flexible key includes a chain of successively hinged knuckles. Some of the knuckles incorporate a first set of key bit projections which extend in the direction of the upright first portion of the curved keyway so as to actuate the first set of tumbler members. Some of the knuckles incorporate a second set of key bit projections which extend in the direction of the cross-wise second portion of the curved keyway so as to actuate the second set of tumbler members.