SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '79eadf9723cc6112185c6ca550ba95619fceb8c8788b570db17d81073586cb37' 
  AND token = 'jOq29R6Qncb1bzDboLgNG5seY9FohO7oEJMlMBnXqmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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