Mixolydian is a great scale to use in a major blues context. It'll give your blues licks a jazzier, richer melodic voice around dominant 7th chords. You can use it in combination with the more signature sounds of the Pentatonic Scales, and you’ll see how the extra notes included in Mixolydian offer great options for newer, fresher licks.
Mixolydian works in blues because it includes all the notes that make up a dominant seventh chord, which is the chord commonly found in basic major blues chord progressions. the chord type used in most major/dominant blues progressions (e.g. G7, D7, E7).
The 1, 3, 5 and ♭7 intervals that make up a dominant seventh chord are what making Mixolydian a great fit to use when improvising.
These can be thought of as targets for your blues phrases and licks, as they connect directly to the backing chords.
The other scale intervals - the 2, 4 and 6 - can be thought of as "color tones" and can bridge the gaps between phrases. If you think of using the notes in this way and you'll never get lost when you improvise your next blues guitar solo!
Be sure to give it a try over the awesome G Mixolydian backing track from Quist, which you should explore for more backing track needs you may have!