{"id":"123456",
 "activities": {
       "activityA": {
                "loginType": "siteA",
                "lastLogin": "2018-02-06T19:42:22.205Z"
            },
       "activityB": {
                "loginType": "siteB",
                "lastLogin": "2018-03-07T11:39:50.346Z"
            },
       "activityC": {
                "loginType": "siteC",
                "lastLogin": "2018-04-08T15:21:15.312Z"
            }
        }
}

SELECT * FROM c where (c.activities[0].lastLogin > '2018-01-01T00:00:00') and (c.activities[0].lastLogin <= '2019-02-15T00:00:00')

SELECT * FROM c where (c.activities[?].lastLogin > '2018-01-01T00:00:00') and (c.activities[?].lastLogin <= '2019-02-15T00:00:00')