Well my dear,
Actually, I don't think that u have to clarify the time in your sentence. Well, the using of " must" in your sentence is true, I have no doubt. I've already read a grammar book writing about this matter. This is similar to conditional sentence
E.g: If I study hard, I can achieve success
Therefore, u can apply present tense in both clauses.
I hope my knowledge may support u!
Student or Learner