The defending champion brushed aside his Slovakian opponent in 57 minutes to reach the last eight.
The Scot blew away the cobwebs with a 7-6 6-4 win over Croatian Ivo Karlovic on Tuesday in his first match since winning last month's US Open and the 25-year-old came roaring out of the blocks, breaking his 65th ranked opponent to love in his opening two service games for a 4-0 lead.
An array of drop shots and sliced passing shots from mid-court left Lacko, who reached the final in Zagreb in February, shaking his head in disbelief but he was gifted a break point when the Olympic gold medallist committed a second double fault.
However the world number three rattled off three points in a row to take the opening stanza in 25 minutes.
The second set followed the same pattern with Lacko winning a mere 12 points in the match and the British number one will meet Stanislas Wawrinka for a place in the semi-finals.
"I started the match almost perfect," Murray said after stretching his winning streak to nine matches in an encounter played with the roof closed as rain from an approaching typhoon lashed Tokyo Bay.
"I only lost a couple of points in the first four or five games. Once I got the break in the second set I started to play better."
Murray, who reached the final of this year's Wimbledon before exacting revenge on Wawrinka's buddy Roger Federer in the Olympic final in London, is not counting his chickens yet.
"He is playing very well just now," Murray said of the seventh-seeded Wawrinka. "I think hard courts are a good surface for him. I expect another tough match."
Wawrinka blew three match points in the second set tiebreaker but came through to beat Frenchman Jeremy Chardy 7-6 6-7 7-5 in two hours, 37 minutes.
"It wasn't easy having (wasted) three match points in the tiebreak," said the 2008 Olympic doubles gold medallist, who served 19 aces.
"You need to be ready to still play the third set and to fight."
Seventh seed Wawrinka praised Murray for breaking his Grand Slam duck after losing his first four major finals.
"He is playing great," said the Swiss. "He won the Olympics, he won the US Open and he always plays great here. It's going to be tough for sure."
Third and fourth seeds Janko Tipsarevic and Juan Monaco reached the second round with wins over Gilles Simon and Grigor Dimitrov respectively.
Argentine Monaco enjoyed a 6-2 6-1 victory in little more than an hour while things were not so simple for Serb Tipsarevic, who lost the first set before coming through 4-6 6-3 6-1. Tipsarevic takes on Marco Chiudinelli in the second round while Monaco will play Marcos Baghdatis.
- Stanislas Wawrinka