You'll get your key fragments in time - here's some of the information that I can recall right off-hand about Honor and Key Fragment Drops.
- Key Fragments still drop at the same rate, barring premade modifiers (at least, I think the premade modifiers don't exist anymore, just don't quote me on that)
- Key Fragments no longer drop exclusively at the end-of-game screen; they'll also drop anywhere in the client, whether you're idling after a few matches or if you just opened it up and logged in. They also have a chance to drop right after a match, too.
- Key Fragments no longer require you to win games - you can lose, and still have your odds of getting a Fragment, thanks to Key Fragment Drops being tied to Honor.
And, some other notes;
- Everybody starts fresh at Honor Level 2. You'll gradually work your way up to Honor Level 3-5 over time, though, if you get penalized by the IFS, you'll go down a level and be locked out of honor gains for a while.
- Consistent honors from your premades will generally not count - Riot built the system to prevent premades from gaming it by honoring each other exclusively, every game.
Altogether, all you really have to do is keep playing, and just expect to see your Key Fragments pop up in the Client sometime soon.
I hope this information helped!