Let's clarify something:
If you have the keyed ignition system where you actually have to insert a key into the ignition to start the car, you are supposed to get two types of keys. One is the regular key with the clicker built into the head. The other is the "valet key" that is just an ignition key without buttons on the head. It doesn't open the trunk. It may or may not have an RFID chip in it, but if it does, it is almost certainly sealed inside the head of the key so that water can't hurt it. It has no button openings to let water in.
If you have the keyless ignition,
you do not have a valet key. You get an electronic clicker (or rather, two of them) that has a mechanical key inside it. You push the little button on the side of the clicker to release the mechanical key, which stays on your key ring. That mechanical key is not a valet key, as it can only open the doors and trunk and cannot start the car. What good would that be to a valet? The mechanical key does not have a chip in it. It doesn't need one.
When you leave your car with a valet, you separate the mechanical key from the clicker and give the clicker to the valet so he can drive the car. YOU keep the mechanical key on your key ring. If you activate the valet button in the trunk, the valet will not be able to get into the trunk without the mechanical key (unless he knows the "secret" way to get into the trunk that makes the whole valet button a silly exercise in futility).
To help avoid confusion, let's all please remember not to refer to any part of the keyless ignition system as a valet key. You don't have one.
Lookit, here are pictures:
