Laravel eloquent get the latest rows of grouped rows

Using Eloquent, trying to find a way to get the latest rows of every row grouped by: exchange, base, quote

Data

exchange    base    quote   price   value   created_at

bittrex     BTC     USD     10000   10000   2018-01-05
bittrex     BTC     USD     9000    9000    2018-01-01
poloniex    BTC     USD     10001   10001   2018-01-05
poloniex    BTC     USD     9000    9000    2018-01-01
binance     BTC     USD     10002   10002   2018-01-05
binance     BTC     USD     9000    9000    2018-01-01
binance     ETH     USD     800     800     2018-01-05
binance     ETH     USD     700     700     2018-01-01

Result:

bittrex     BTC     USD     10000   10000   2018-01-05
poloniex    BTC     USD     10001   10001   2018-01-05
binance     BTC     USD     10002   10002   2018-01-05
binance     ETH     USD     800     800     2018-01-05

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