HAD we but world enough, and time, This coyness, Lady, were no crime (lines 1-2)
This sets us up for later, when the speaker reveals that he thinks "time" is a criminal who terrorizes him. It’s interesting that the speaker doesn’t call the lady a criminal directly, but just says that she wouldn’t be one if they had more time. Notice how all of his accusations follow that form.
Time's wingèd chariot hurrying near (line 22)
Things changed a lot since the 1650s – now time has a winged Mazerati! Still, it’s an interesting idea that time has a vehicle, and that time moves and travels. The speaker needs this indirect personification in order to think of time as the super-villain pursuing him. It’s no surprise that time would take a front-row seat in Marvell’s imagination. In his day, there is a revolution in timekeeping, and "accurate" clocks are just beginning to be made.
Deserts of vast eternity (line 25)
This is a striking metaphor, which seems somewhat confusing when we start to break it down. The speaker doesn’t compare eternity to "deserts," but talks about deserts that are made out of eternity. We don’t know what eternity looks like. It’s an abstract idea, like time. Deserts come in many varieties, but, here, the desert is a symbol of emptiness and loneliness. This line also plays on the idea of an hourglass, and "the sands of time."