SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5afc7a4207670884e12d64fb1e04f0968fffc13f306684894ba29c9958c1df88' 
  AND token = 'REbABjweTiJv+kuMKZ2fIq/+W3HORtaC+pi1nBnon9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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