The 23-year-old was drafted in by national team boss Alex McLeish for the first time after Millwall’s Jordan Archer was forced out through injury.
The former Rangers shot-stopper has flourished playing in his debut Premiership campaign and has kept a total of 15 clean sheets this term.
Former Scotland midfielder Holt insists Kelly’s commitment to bettering himself is refreshing.
He said: “I’m over the moon for him, it’s a feather in the cap for Liam and a feather in the cap for the boys and staff at the club. It’s another added bonus for him following on from the exceptional season he’s had.
“Liam is a sponge when it comes to football, he loves talking about it, asking questions and picking your brain about things with regards to the tactical and technical side.
“He wants to know and it’s really endearing to see how infectious he can be at times, but sometimes you need to tell him to take a step back and switch off because he just loves it so much.
“We’re delighted as a club that we’ve given him that chance to go and play at this level – and he’s improving day-in, day-out.
“Thankfully Alex has taken the decision to call him up and I’ve no fears over him. He’ll go there, I’m sure he will take to the international scene like a duck to water and we’ll get the benefits when he comes back.”
Holt insists the success of Kelly’s own season is also down to his team-mates and the coaching staff.
He added: “It’s a great achievement with the clean sheets we’ve had and it’s testament to the lads in front of him as well.
“The work they put in day-in, day-out is tremendous and we get the fruits of that labour on a Saturday but it comes from what they do Monday to Friday and how hard they work.
“Liam certainly epitomises that with his work rate and performances on match days and I’m really delighted for him. But it’s the first step getting called into the squad, now he’s got to go and impress and take the chance.”