“The Senate is a place filled with goodwill and good intentions, and if the road to hell is paved with them, then it's a pretty good detour.”

April 14, 1775
Malone added a footnote indicating this is a "proverbial sentence", quoting an earlier 1651 source. At least two other sources appear prior to Johnson. John Ray, in 1670, cited as a proverb, "Hell is paved with good intentions." Even earlier than that, it has been attributed to Saint Bernard of Clairvaux (1091-1153), as "Hell is full of good intentions or desires."
[alt.quotations, Earlier Attributions, Wilson, Robert, UseNet, 2009-01-06]
Note that "The road to Hell…" is not part of the quotation.
The Samuel Johnson web site suggests this entry is dated 16 April, but it appears to be part of the previous entry.
Samuel Johnson web site http://www.samueljohnson.com/road.html
Life of Samuel Johnson (1791), Vol II
Source: The Life of Samuel Johnson LL.D. Vol 2

No Compromise – No Political Trading (1899)

Alex Lightwood, Simon Lewis, and the Seelie Queen, pg. 353-354
Source: The Mortal Instruments, City of Heavenly Fire (2014)
Context: There,' he said, pointing to the leafy tunnel. 'That goes farther into Faerie. And that'--he pointed ahead--'is the road to Hell. That's where we're going.'
'I always heard it was paved with good intentions,' said Simon.
'Place your feet upon the way and find out, Daylighter,' said the Queen.

Marcellus Wiley: NBA plan to paint 'Black Lives Matter' on courts 'not a good idea' https://www.washingtonexaminer.com/news/marcellus-wiley-nba-plan-to-paint-black-lives-matter-on-courts-not-a-good-idea (June 2020)

Vol. I, Ch. 7, pg. 213.
(Buch I) (1867)

Source: On Writing: A Memoir of the Craft

As quoted in "Works in Progress" in The New York Times Book Review (15 July 1979), page BR1

Variant: All right. Have it your own way. Road to hell paved with unbought stuffed dogs. Not my fault.
Source: The Sun Also Rises (1926)