SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '021781accc3c8a65854ff0608db155f1fd935db8811a0e4c52fca462c32aaa77' 
  AND token = 'ccoycK8sTFga8PdIkA2YzvWDjeeFVFjMQfPLzNkmPwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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