SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'df22ccaa054b4a6db1754da751fd36571915f46892fe571c380eb1f3bcef88bc' 
  AND token = '8YJ4rDDKu5J/nrk4XFrXJ+LdXXBNjlbqAHhiS5SU6vE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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