The striker refused to rule out a Rangers return last weekend after Ibrox manager Ally McCoist admitted live on television that he was planning a summer bid for the out-of-contract 30-year-old.
Johnston has yet to receive a call from McCoist spelling out if he will be offering Boyd a deal but acknowledges the former Scotland player has ambitions to play at the highest level he can.
However, the Ayrshiremen’s manager hopes his team can offer the 19-goal frontman a suitable platform to show off his penalty-box talents.
He said: “I don’t know what will happen with Kris. He’s enjoying his football here. The club will try its best to keep him because he is such a massive player for us.
“It’s all just speculation so there’s no point talking to him about that. He is focused on the job ahead, which is getting points for Kilmarnock.
“I’m sure it won’t just be Rangers who is looking at Boydy with the amount of goals he has scored. But we think he’s happy here and will try to keep him for longer. I have not heard anything from Rangers. I would imagine they would contact us to tell us if they had been talking to him. But you never know.
“There’s a lot to be said for enjoying your football, though. He’s a Kilmarnock boy and I know he has loved his time here, so we can only try our best to convince him to stay.
“I know guys like Kris want to play at the highest level for as long as they can.
“We need to make sure we are challenging up the top end of the table if we want to keep hold of our best players,” added Johnston
Kilmarnock face third-placed Motherwell tomorrow after successive defeats to Celtic and Aberdeen.
But Johnston – whose side sit three points above the relegation play-off spot – is not panicked by the quirk of the fixture list which pitted them against the Scottish Premiership’s top three teams back to back.
“Everybody has to play these top teams and, at this stage of the season, there are no easy games,” said Johnston. “Every game is a cup final for us now and we need to make sure we play it that way.
“But we have players who can hurt Motherwell and we think we have got a good chance of winning the game.”