the benefits of cardio are maximized up to one hour after the cardio session ends - depending on heart rate.
If you're following a ketogenic diet, consume a protein drink about 30-45 minutes afterwards. Otherwise, consume a portion of protein and a portion of carbohydrate 30-45 minutes afterwards.
I prefer to wait about 1 hour after completing cardion, especially if it is performed first thing in the morning. Eating sooner will just hinder the benefit that occurs after cardio is completed.