Dogshoes? No seriously, you can use Tuff Pad or Tuf-Foot. It's like a medication, made up of mostly natural ingredients and it helps to toughen up the sore or cracked or burnt pads of your best friend.
You can buy dog shoes from Amazon.com but I really recommend that you take your dog for a long walk in the early morning when the heat from the asphalt is not a problem. The damage to his pads is not the main problem. The asphalt gives off a lot off heat for many hours after the sun is set and since dogs do not sweat as easily as we do they are likely to overheat. The pad protectors will not keep your dog from heat stroke.
Early Morning walks are the best bet, late evening walks can be okay too. Here in Vegas in the summer the pavement can be 150 degrees by early afternoon and is hottest later in the afternoon. Hotter than the air temp. from soaking up the sun.