Straight eighths — the most basic rock keyboard part: both hands hammer the chord on every eighth note, right hand in close position, left hand on the root. Nothing is syncopated; the energy comes from the evenness and from the drums underneath.
How it sits: the drums play the rock backbeat — kick on 1 and 3 (with an extra kick on the and of 3), snare on 2 and 4, closed hi-hat on every eighth — so the piano eighths lock to the hat. The bass doubles the left hand in eighths; bar 2 splits into F and G, half a bar each.
Listen for how flat the dynamics are: no accent on the downbeat, a slight lift into 2 and 4 with the snare. Keep the eighths short and even — the chord should sound like a pulse, not a melody.
Practice: play right hand alone with the hat, then add the left hand on the same eighths without letting it turn into a swing.