A valet car key is a key that only works on the car's ignition and door locks. The key is cut differently from the latch on the rear of the vehicle, so it will not allow a valet to open the trunk without the owner's consent.
Valet keys are often paired with the driver's key when a vehicle is purchased. If the valet key is not handed with the driver's key it may be in one of two locations. The first place to check is in the vehicle's owner manual as the key may be stuck inside. Another place to check is inside the vehicle's emergency tool kit located in the trunk.