This is a query that returns a result for me:
{"method": "call", "params": [0, "get_trade_history", ["BTS", "USD", "2018-12-17T16:13:49", "2018-12-16T16:13:49", 10]], "jsonrpc": "2.0", "id": 3}
It requires the market_plugin to be enabled on the backend. Try against "wss://node.bitshares.eu"