The former Bristol City striker has been linked with a move away from Upton Park, but McDonald isn't expecting the 25-year-old to be going anywhere.
"He is involved all the time, he is on the bench. Nothing that I have heard [suggests he won't be here this time next week]," said McDonald.
"He is an important member of the squad and he has put in a good performance today and given the manager something to think about, that's for sure."
Maynard scored the opener in West Ham's 2-0 Capital One Cup victory over Crewe Alexandria.