Car will lock with key inside car!
You have two keys. If one key is in the car, you can lock the car with the other key. I always do this and my wife keeps her keys in her purse as she likes to leave it in the trunk while shopping.
However, I must admit that the car can be locked even with one key in the car and no keys anywhere around the car. I had that happen to me once while I was at a gas station washing my car with the keys in. I went and grab the handle trying to open the door but touched the sensor and the door locked. I had to take a cab back to my house and grab the other key to unlock the car.
However, this never happened again. I am sure that was an one off but it can still happen.