A combination of a disc tumbler cylinder lock and a key. The disc tumbler cylinder lock includes rotation limiting device for the key and a guiding element. The key includes grooves for the guiding element, which has two rails making up some of said rotation limiting device, and both of the rails include at least one limiter protrusion arranged to facing inward in the disc tumbler cylinder lock. The key includes at least one recess for the limiter protrusions. The rotation limiting device further includes a front guide having the rails in association therewith. The front guide and the rails are arranged to allow the key, which is in a basic position in the disc tumbler cylinder lock, to be turned for releasing the locking of the disc tumbler cylinder lock.