Key switch for safety-related applications, in particular for the deactivation of an airbag, - with a switch housing, - with a lock cylinder, which is rotatably arranged about a rotary axis in the switch housing and comprises an axial key opening for axially inserting a key and an insertion channel open to the key opening, - with a locking element arranged in the switch housing, which can be switched by means of the key from a locked position to an unlocked position and which is urged into the locked position by means of at least one spring element, - wherein the lock cylinder can be rotatably adjusted between a first shift position and a second shift position by means of the key, if the locking element is in the unlocked position, - wherein the lock cylinder is secured against rotating with respect to the switch housing by the locking element placed in the locked position, - wherein the locking element for shifting between the locked position and the unlocked position is arranged axially slide-adjustable with respect to the switch housing and with respect to the lock cylinder, - wherein the lock cylinder comprises at least one radial guide opening which is open to the insertion channel, - wherein the locking element comprises at least one retaining contour radially protruding through the respective guide opening into the insertion channel, - wherein the locking element is slide-adjustably guided via the respective retaining contour in the respective guide opening at the lock cylinder parallel to the rotary axis and is secured against rotating about the rotary axis, characterized in that the locking element has a ring-shaped configuration and is coaxially arranged with respect to the lock cylinder and surrounds the lock cylinder. - with a switch housing, - with a lock cylinder, which is rotatably arranged about a rotary axis in the switch housing and comprises an axial key opening for axially inserting a key and an insertion channel open to the key opening, - with a locking element arranged in the switch housing, which can be switched by means of the key from a locked position to an unlocked position and which is urged into the locked position by means of at least one spring element, - wherein the lock cylinder can be rotatably adjusted between a first shift position and a second shift position by means of the key, if the locking element is in the unlocked position, - wherein the lock cylinder is secured against rotating with respect to the switch housing by the locking element placed in the locked position, - wherein the locking element for shifting between the locked position and the unlocked position is arranged axially slide-adjustable with respect to the switch housing and with respect to the lock cylinder, - wherein the lock cylinder comprises at least one radial guide opening which is open to the insertion channel, - wherein the locking element comprises at least one retaining contour radially protruding through the respective guide opening into the insertion channel, - wherein the locking element is slide-adjustably guided via the respective retaining contour in the respective guide opening at the lock cylinder parallel to the rotary axis and is secured against rotating about the rotary axis,