You have 4 options,
1) If your the original owner, and you have the owners manual, you can order a key from a reputable locksmith by ordering via the key code on the security card, but it will need to be programmed in to the car, by a reputable locksmith.
2) Call a mobile locksmith to attend that can program keys into vehicles,
3) Arrange it to be towed to a reputable locksmith.
4) Arrange it to be towed to dealer (if there is one in a town near you)