Time to get dextrous ninjas. Commit to a practice regimen, share drills that have worked for you, or moan about your carpal tunnel and tendonitis.
I just recently got an MPK61 and have embarked on the journey to become a good pianist. I've played several instruments before so I have a strong grasp of music theory, I just need to bring myself up to speed technically. To start off, I'm trying for 1 hour of practice a day. At the moment it's comprised mostly of technical drills, although I do some ear training and note memorization while my hands rest.
To build that initial digital agility and coordination, I've been doing 5-finger drills. Here's a link to the Hanon exercises I've been using. Basically just been working through them slowly. Learning them for each hand individually and then combining the two. Starting off very slow to imprint it cleanly into muscle memory, and using a metronome to keep it rhythmically tight. I double the metronome speed and play eighth notes instead of sixteenths so there's an extra tick in the middle of each grouping. Also if you use the Hanon drills, disregard the part about lifting your fingers high, you should be training them to be economical with motion. You don't want to ingrain the habit of having your fingers too high above the keybed since it'll just waste energy and slow you down in the future.
After my hands get a bit more coordinated, I'll be moving towards scales, modes and arpeggios. I drew myself up charts for each key, containing the parent scale and all 7 modes of that scale and their accompanying arpeggios. I'm just gonna work in a new key every day, rotating around the circle of fifths.
Interval training will be part technique, part memorization, and part ear training. Basically ascending and descending scales, jumping by various intervals. Good practice for making leaps with your hands and good relative pitch training.
Then I'll throw in some chord voicings and inversions to get comfortable playing and transitioning between them. Practicing transitioning from each chord in a key to every other. Similar to interval training but with full chords on top of the root notes.
After doing all of the above for a couple months I should be a fairly competent pianist. I might learn a few songs for extra practice but I come from the jazz improv side of things so I'll probably just be jamming and composing. The great thing about being a producer is that you can use a lot of tools to help you practice. All DAWs have a metronome built in and you can easily record midi to assess your progress and see how tight you're playing. Recording yourself is a really important thing to get better and a lot of instrumentalists neglect to do it. You also have the ability to build your own backing tracks for things like improv practice.
Just a couple months with short practice sessions every day will radically improve your playing. It doesn't have to be an hour, you can just play scales while you wait for a video to load or wait to respawn in Battlefield. Every little bit adds up. I see this as probably the easiest way to measurably improve your skills as a producer. In comparison to arranging and mixing, learning performance is considerably less tedious to practice. It'll also make it much easier to compose, as well as speed up your producing time, especially during that vital first hour after the spark. Jamming on keys is much more inspiring than looking at a piano roll. If you're a skilled player, playing will be fun, and the more you play the more opportunities for inspiration to strike.
Commit to a month and see if you end up with something other than turds to polish.
Worst case scenario you just end up getting attention from the ladies for your strong agile fingers.
there is no ability to sight read (I can barely read sheet music without stopping and counting notes haha) 
), a small casio keyboard and a horribly out of tune piano to play on, all of which feel totally different. 
