I came here to see if what I've been studying is going to pay off

You study for an exam but it's one of those exams that are unpredictable and whether you pass or fail depends more on luck than anything. You get to the classroom and you say:

I came here to see if what I've been studying is going to pay off or not.

Are "I've been" "is going to" correct even though I used "I came"? I've heard people use "came" instead of "have come" and I know my sentence would work with "have come". Thank you very much ??