Could I e-mail my professor and ask what my final grade will be before I graduate in two days?
If you're concerned about your grade, then you can try to send a polite email. However, you may also want to check if there's a policy whereby grades for graduating seniors need to be turned in early (which may or may not be the case, given the need to make sure students can graduate.

If not, the grades might not be ready, if the submission deadline has not yet passed. (But how can they schedule graduation before grades are due?) 

Also, the answer may depend on how large the class is: the bigger the course you're worried about, the less likely the grades will be ready early.