Many phones that claim 32GB max will support a 64GB card formatted as FAT32. (The speed depends on the card and the phone - mainly the card - not on whether the phone claims to only support 32GB). There are two notes of caution here:
1) I doubt that the phone would support the crd if it were formatted exFAT64.
2) Not all phones that claim to support up to 32GB will support a 64GB card, even formatted as FAT32. Most of them will report no card inserted.
Moral of the story is to borrow someone else's 64GB card to try in your phone before you spend the money for one.
And if you want maximum performance, get an Extreme card. (Speeds range from Class 1 [slowest] to Class 10 to Ultra to Extreme[fastest].) Right now, only SanDisk makes Ultra and Extreme cards, but that's okay, since they're the best SD card company on the market anyway (and only one of two manufacturers of the chips that go into the cards).