The Lilywhites found the back of the net with their first attack in the 5th minute; Pádraig Fogarty shooting home from close range.
Kildare’s lead was nine points by the 15th minute before Longford created a goal chance; Brian Kavanagh’s ball found McKeon but his fisted effort went wide.
Cian Mimnagh got their second point in the 30th minute but with Eoghan O’Flaherty in fantastic form the Lilywhites went in at the break 12 points in front.
The second half was mere target practice with Kildare adding two more goals through substitutes Mickey Conway in the 49th minute and Darroch Mulhall in the 67th minute.
A dismal Longford side fired over just four points after the break.
KILDARE: S Connolly; M O’Grady, M Foley, J Kinahan; K Murnaghan, F Conway, P Cribbin; G White, T Moolick (0-2); C Canning, E O’Flaherty (0-7,2f), C McNally (0-2); C Murphy (0-2), R Dunne (0-3), P Fogarty (1-2).
Subs: C Tiernan for Cribbin and M Conway (1-1) for Murphy (46), D Mulhall (1-1) for Dunne (57), M Konstantin for Foley (61), S Campbell for Kinahan (63).
LONGFORD: D Sheridan; D Keogh, F Battrim, A Rowan; G Farrell, F Reilly, G Smith; K Diffley, J Keegan; B Farrell, D Cooney, P Gill (0-1); P McKeon (0-1), B Kavanagh (0-3,1f), C Mimnagh (0-1).
Subs: CP Smyth for Smith (21), P Brady for G Farrell (ht), S Doyle for Farrell and R McEntire for Gill (46), S Kiernan for Diffley (49), S Cox for Keogh (59).
Referee: N Ward (Westmeath)