The out-of-contract manager still does not know if the Jambos chairwoman-in-waiting Ann Budge will give him a fresh deal after he failed to prevent the club's relegation from the Scottish Premiership.
But a week after watching his side beat city rivals Hibernian for the fourth time this season, Locke was left beaming as Killie were slaughtered in the capital.
Ryan Stevenson netted a first-half hat-trick before teeing up Billy King and Callum Paterson to extend the Gorgie side's impressive unbeaten run to six games - five of which have been victories.
Hearts' fans lapped up the entertainment and chanted "bring on the Rangers" as they looked forward to next season's second-tier campaign - but it was a miserable day for Killie.
They had beaten Locke's side in each of their three previous meetings this season but the defeat means they remain rooted in the relegation play-off spot, a point behind Ross County and two back from Partick and Hibs with just two games remaining.
St Mirren will have cheered the result all the way from Paisley too as it means the Buddies are now guaranteed a ninth successive season of top-flight football next term.
Hearts started with purpose and were handed their opportunity to strike after just 11 minutes when Sam Nicholson was barged over by Ross Barbour outside the left-hand corner of the Killie box.
Stevenson shaped to swing a cross in from the set-piece but instead drilled a firm drive through the defensive wall, leaving keeper Craig Samson helpless as the ball fizzed past him into the far corner.
Hearts remained in command and doubled their lead on 24 minutes.
Nicholson was fed the ball down the left by Kevin McHattie but saw his low cross cut out by Vitaljis Maksimenko. The Latvian failed to get enough distance on his clearance though and Stevenson rammed the ball back with interest from 20 yards out as he beat Samson for the second.
Kris Boyd had struck doubles in his each of his three previous outings against the Jambos this season but saw his best chance saved on 35 minutes as Jamie MacDonald reacted well to his low drive.
Killie winger Chris Johnstone wanted a penalty when he stumbled after failing to outpace Paterson down the left. Referee Calum Murray waved away his appeals as the Jambos full-back wagged a disapproving finger in the teenager's face.
Stevenson was denied a third by Samson as half-time approached, but he did cap off his treble in stoppage time when King drove to the byline before cutting the ball back for the 29-year-old to slide home from eight yards.
Stevenson was cheered off as a hero when the whistle went at the interval but the disgruntled Ayrshire support displayed their anger with a chorus of boos.
And there was no let-up in their frustration as Kilmarnock were easily cut open again soon after the restart. A post saved them on that occasion as Stevenson failed to net his fourth after combining cleverly with Nicholson.
But he did not let that miss distract him and on 56 minutes he swept over a sublime pass to put King in behind a Killie defence who were at sixes and sevens. With just Samson in the way, the winger made no mistake as he slammed the ball into the far corner.
By this stage the visitors were a complete mess at the back and allowed Stevenson time and space down their left to roll the ball across the six-yard box for Paterson to add number five from close range after an hour.