Why there is a delay in buy order execution?

Hi, when I place an MIS buy order at 09:15:15 seconds, the order is excecuting at 09:15:45 seconds, even though the order is a market buy order. Because of the late order execution I got loss two times.

The same question has been answered on this link here: Why do market orders and AMO orders delay execution at 9.15 when the market opens?