That's not what the move says.
A move applies when it's fictional description happens, and there is a significant difference between “[a] character comes to you for advice” and “[a] player […] asks [you] questions”. So, if the other players just ask you any random question at the table, this move does not trigger, and no imbalance is done.
However, if another character is actually under attack, turns to the wizard (who might be busy with her part of the fight), interrupts her and asks her what to do, this move could possibley trigger, and all the other implications of the fiction would have to trigger as well, in particular that the wizard now pays attention to the other character's foes and not her own situation (how else is she going to give advice), the advice seeker could be directing attention of his foes to the wizard, etc.
(Obviously, “Coming to someone for advice” in the real world normally imply “having a conversation”, “being in a somewhat private environment”, “spending some time thinking about the alternatives”, “expecting the advisor to have relevant knowledge” etc., so it might not actually trigger, depending on your table. But even with minimal assumptions, which allow triggering the move in the middle of a fight, doing so would definitely constitute a Golden Opportunity for the GM, which should remove your concerns about this move.)
In general, the clear implication of this move is that the wizard has a large amount of experience and/or knowledge, and is therefore qualified to give helpful (thus the +1 forward) advice in any (Note how the move is called Know-it-all and does not contain a restriction such as “for advice about …”) situation.