A key including a retractable shaft mounted pivotably with respect to a case forming an operating head of the key, between a retracted position in which the shaft extends in a substantially longitudinal direction inside a housing of the case, and a deployed position in which the shaft extends outside the case. The shaft has a first end forming a heel by which the shaft is pivoted about a vertical pivot axis orthogonal to the axis of the shaft. The key includes a drive mechanism for driving the shaft toward one of the retracted position or the deployed operating position. The drive mechanism includes a resiliently deformable element, which exerts a resilient force to return the shaft toward the retracted or deployed position, according to the angular position of the shaft with respect to an intermediate position of the shaft between the deployed position and the retracted position.