Thank you for choosing Just Answer, my name is Jon and I will do my best to help you find the answer you need to resolve your problem.
I can't seem to find a listing for your snowblower, but there are not many keys out there.
Here are the most common ones starting with the Murray ones;
Universal turn style metal key
Set of all old keys
If none of these look familiar I can supply you more number tomorrow from work. A picture of your key would help greatly if you need further assistance