The closest to what you want is probably "천만에요". I typically say "별말씀을요" if I'm formal or "아니다" for informal. Can't really think of any phrase that says both "it's okay" and "you're welcome". Hope this helped!

In Korea if you say "You're welcome" after they've apologized and thanked you they'll probably thank you again or not understand why you said it. If somebody apoligizes to you and thanks you then the best response would be "Yes" in Korean: "네" pronounced "Ne". If you want to be more warm in your reply then add a smiley face with it.