Yup, wrote in a rush sorry. I meant if it had an AND clause. In which case I would hope the index was checked first. I assume that would be faster? It would be less generic though, coding-wise, as it would mean you now have the special case where you check whether the column(s) are indexed before you decide which conditions to check first.
All I'm saying is that internally I don't know if the DB is written for speed optimization, or more generic programming.