SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dfa47647ffa099b8a814b8641e43b558f2769a1af07ea250d62e947c4fa6da9' 
  AND token = 'hEj8twkTFeHaUaF+br8gs70pWolu/7qBKlhsiL5MUM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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