The Wales international said he "literally died" when he collapsed in the 59th minute of the game, which was abandoned, just seven months after falling to the pitch in a similar incident in the Championship playoff final at Wembley.
"I woke up and the paramedics and everyone was everywhere," Lockyer told Sky Sports ahead of Luton's home game against Manchester United on Sunday.
"I could see straight away... there was a bit more panic around and I was a bit disorientated. I couldn't speak, I couldn't move and I was just trying to take in and work out what was happening. I remember thinking, 'I could be dying.'
"That's a surreal thought to have and not be able to move and respond, and you can see the panic and feel the drip being put into my arm," he added.
"It was all quite a hard mix of emotions, eventually I came around and was able to speak and respond. I'm just fortunate it happened where it happened. I feel like everyone watching it and my family had it worse than me."
Lockyer said the recording device he had inserted after his collapse last May showed he "was out" for two minutes 40 seconds in December's cardiac arrest and that he needed a defibrillator to revive him.
Adding to the emotions, his girlfriend was seven months pregnant at the time.
Lockyer said whether or not he can return to playing is out of his hands, but he remains hopeful.
"That will be dictated by medical staff and specialists, but what I would say is that if there is a chance - obviously I won't do anything against specialist recommendations - then I would love to.
"Obviously it's far too early to say at this time, there's a lot more tests that need to happen. But I wouldn't write it off at the minute, but my priorities are with the baby."
Lockyer has spoken to other players who have returned to the pitch with similar heart conditions including Christian Eriksen, Daley Blind and Charlie Wyke.
"The one thing that was common from them all was, 'Take your time to process what has happened,'" Lockyer said.
"In some ways, I don't think I have processed it, maybe because as athletes we're able to deal with things differently and can compartmentalise.
"Maybe it will come back and bite me on the bum, but I've not really had any emotions since, I know I literally died but I've been quite numb about it. But my girlfriend is pregnant, due soon, that's my priority."