Array of objects convert to object with keys by item field value

I have this array:

const demo = [
  { key: 'apple', a: 'b', c: 1 },
  { key: 'banana', a: 'f', c: 3 },
  { key: 'orange', a: 'j', c: 8 },
];

I can get info about “banana” by using:

demo.find(item => item.key === 'banana')

Instead I would like to have this associative and access like this:

demo.banana.c

So I need to somehow get this:

const demo = {
  'apple': { key: 'apple', a: 'b', c: 1 },
  'banana': { key: 'banana', a: 'f', c: 3 },
  'orange': { key: 'orange', a: 'j', c: 8 },
};

Or without “key” inside, it does not matter.

What would be simplest solution? Some simple (maybe one-line) approach with ES6? If not, Lodash instead?