SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31f4b2889c53c39d55da1d35cb43958d112dcde8c4041117f01ff887eb656d6a' 
  AND token = 'N6NHthz5oTb8egjwjoRch5ssHGXGRqHWIQUwDjICGiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}