SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d4502b43765d07210f94b9f0302b9db3589460b34cee4c5934998a119317407' 
  AND token = 'e/8SiBtraPlh7fCFpW4H9jtcu/E27+uMP2dxqmrirQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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