Early in the second half and with the Hatters 2-0 to the good, visiting sub Aidan Nesbitt was left unmarked and a mere eight yards out.
Faced with just Isted to beat, his first attempt was excellently parried by the keeper, making only his second appearance for the club, while the second one shot looked destined to halve the deficit, only for Town's stopper make a quite stunning effort with his left hand to deflect behind for a corner.
It enabled Luton to keep the two-goal lead, an advantage they shortly added to through Jorge Grant, and when asked about the stops, Jones said: “They came at a key time as well as they’d just come out of the blocks,
"It was two point blanks saves that he had no right to make, that’s what sometimes your keeper has to make and that’s what he did.
Jones could loan out Muskwe and Mendes Gomes as he admits certain players would have left regardless of cup exit
Jones still keen on pushing for defensive signing ahead of deadline day
Luton boss will make a late decision in the transfer window on whether to loan out Pereira
HATTERS RATED: Luton Town 2 Newport County 3
Former Aston Villa and Crystal Palace youngster Williams elated to make his full Hatters debut in Carabao Cup
"We’ve given him credit in there (dressing room), because that gave us the platform to go on.
"They came out with intensity, made three changes, they knew they were nowhere near first half so they’ve made those and brought something different on.
"They came out of the blocks and credit to them, we then had to readjust, come off the press, let them have it in there and then hit them on the counter and we did that all second half.
"Our gameplan was excellent, I thought we executed it superbly well and we were well, well worth the result."