SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '326d2f500495dc7dacf899efb54cfa32ae18c054522cf1458e793af3049791d2' 
  AND token = 'nhM7hioDeM67bYCreAixMIv+xEgtVrDA2AIhG/9wli0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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