The defender has been linked with a return to former club Barcelona, along with a move to the Premier League.
But Mourino told AS: "The clauses are always there and anyone can pay them.
"Mingueza is an important player in the team, in the dressing room, being an international and I see him so happy here that it is hard for me to think that he could leave, but so many things happen in the market that maybe tomorrow they will call me and tell me that they have paid the clause.
"I think he will stay with us."
Mourino also commented on Iago Aspas' new contract announced on Christmas Day: "I'm super excited. The truth is that everything has been so easy with Iago, how he has welcomed the youth players, how he teaches them and demands them with his leadership.
"We insisted on the renewal and he asked us for time, that he would only renew if he was okay, that he wasn't going to stay one more year just to stay. That involvement is not common. It has been a gift for the fans. He is a legend forever."