Unless I got it wrong (the name appears to be spelled without an "H"), there were 3 games released according to Wikipedia:
In 1991, Hi-Tec Software published Jonny Quest in Doctor Zin's Underworld, a licensed Jonny Quest platform game for the Sinclair ZX Spectrum, Amstrad CPC and Commodore 64 home computers.
In 1993, Hollyware Entertainment published "Jonny Quest: Curse of the Mayan Warriors," a licensed title available only on 3.5" floppy disk. The pre-release title was "Jonny Quest and the Splinter of Heaven."
In 1996, Virgin Interactive published Jonny Quest: Cover-Up At Roswell for Windows 3.1 and Windows 95.
There may be videos on YouTube for them.