The former University of Kentucky star hit up Catch in L.A. for dinner and EVERYONE noticed when he pulled up ... behind the wheel of what appears to be a McLaren 720S Spider, which usually carry a $300,000 price tag!!!

You gotta watch the video with the SOUND ON -- the engine purrs like a tiger ... it's incredible.

We asked Johnson if he's rooting for any particular team to draft him in June -- and he gave the answer any smart future NBA star would give!!

Many experts predict Johnson could be selected between the 10th and 25th pick -- which means his rookie contract with likely be a 4-year deal worth anywhere from $10 to $20 MILLION!

Johnson has been a stud basketball player for years -- he was ranked in the Top 15 high school players in the country back in 2018 ... and when he got to Kentucky, he led the team in scoring for most of the season.

He started 36 out of 37 games in his freshman year -- averaging 13.5 points per game in college with 5.9 rebounds.