SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8c5709c2b313fdc6779feed7323dcfe3320f46f689a53b52f09c08547561d74c' 
  AND token = 'M8qodSQBgHPp6JXkvy7m3bW+5P7+5aivHmONXtHeJSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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