MKT has timers. Your ability to play the game is gated behind a "hearts" currency. Every start of a race costs one heart, and your default meter maxes out at five hearts. It takes roughly 12 minutes for a single heart to refill, while the game's opening portion constantly refills hearts as part of the early leveling-up process. It's unclear at what point this ample heart supply runs out and players are stuck either waiting on timers or spending an "emerald" currency for more hearts, which can either be earned in-game or (eventually) paid for with real-world money.
Additionally, the game's progression system to access new racetracks, through a single-player campaign, is hard-gated by its own set of timers. As I type this, I'm waiting a full hour before I can unlock the game's "Toadette Cup" of three racecourses, even though I've otherwise met its requirement of other progress. There's no way to pay in-game currency or real-world money to speed that unlock up.
MKT also has loot boxes. The game's aforementioned emeralds are required to access the game's loot. Spend five emeralds (no idea how much that will cost in real-world money) to get a single, random unlock of a mascot character, a go-kart model, or a "glider" accessory. Unlike past games, differing characters and karts don't appear to come with standard control trade-offs like strength, acceleration, top speed, and so on.
Instead, each of these pickups vary in "rarity"... and that rarity indicates how much they affect major racing factors, including: top speed, coin-earning rates within a race, likelihood of picking up mid-race weapons and items, ability to hold multiple mid-race items at once, and multipliers for your "driver points" (DP) total at the end of a race.
