Back from the front?
Actually, I don't understand it, either.
I will say that you should not put apostrophes around numeric values (e.g, '74763') unless the field you are inserting into (in this case, user) is *NOT* a numeric data type.
But that shouldn't cause more than a millisecond or two of extra time for a single insert.
I am wondering if perhaps you are doing this on an overloaded server.
Instead of looking at the query time, look at the lock time: 0.000085, or 85 MICROseconds. In other words, that's all the time that MySQL used to lock the needed DB elements while performing the INSERT. So where did the other 2 seconds go? Possibly into simply waiting until the table was unlocked by some other user or process?
Are other kinds of queries on this database similarly slow? Or is it just the inserts?
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.