Home protests against chairman Michael Johnston's stewardship were again in evidence, but there was no disputing the home side's dominance on the pitch over rock-bottom Hearts.
The hosts were rewarded for an impressive start as the predatory Boyd latched on to Sean Clohessy's long ball, cut inside Jordan McGhee and slotted low past Jamie MacDonald (17).
Jackson Irvine directed his header to close to MacDonald before Killie's Darren Barr had to be stretchered off after an accidental clash of heads with Callum Paterson.
His departure did not upset the hosts hegemony; Barry Nicholson heading wide after more good work by Michael Gardyne.
In a rare Hearts threat, Kevin McHattie's deflected shot was knocked on by Paterson but Danny Wilson could not connect just five yards out.
MacDonald had to produce a fine reaction stop to deny Chris Johnston while Paterson threatened again for Hearts, but he could not provide the decisive touch after good work by Jamie Walker.
But the force was with the home side and Boyd (64) was again the executioner, latching onto Jeroen Tesselaar's free-kick before flicking home from 14 yards.
Boyd then teed up Johnston whose effort was palmed over by MacDonald while Boyd was inches away from a hat-trick as Hearts slipped to their sixth defeat in their last seven league games.