If the wicket-keeper misses the ball and it travels all the way to the boundary, the batting team scores four byes, just as if the batsman had hit the ball to the boundary for four runs.
If the wicket-keeper misses the ball and it travels all the way to the boundary, the batting team immediately scores five wides, similarly as if the ball had been hit to the boundary for a four on a no ball.
0.063 seconds.