Locking device having first and second combined connection carriers for establishing a detachable connection. A rotation element is rotatably attached at the first connection carrier and is provided in an inner region thereof. The inner region is centered with respect to a center axis and has a full radius. Elastic blocking heads are attached at the first connection carrier at the inner region, and are movable from a blocking to a release position. The rotation element includes segments extending up to the full radius and segments extending at a maximum up to a smaller inner radius. The segments extending up to the full radius move blocking heads into the release position and the segments extending up to the inner radius leave blocking heads in the blocking position. Key tongues move bordering ones of the blocking heads into the release position and allow rotation of the rotation element.