your best bet is to go to your local toyota dealer inform them of your situation. its more than likely they have a blank key laying around that can be cut or programmed depending on the year of the car ,worse case they can over night one and programme it the following day
Typically the best place to buy a new key is from a dealer. There are probably people selling them cheaper online however it is a better idea to get them from a dealer. They can use your vin number to order the exact key for your vehicle.
If you are wanting to replace the master key to this type of vehicle then you will first need to contact your dealer. If your dealer is not able to provide you with the key that you are looking for then you can contact your local dealer to see if they have it.