SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fe9f763b8558e3eabea4dacd9c1689cae1eef54fb2765e3feaecf16c061b794a' 
  AND token = 'slhh/UUuf5VfO3X5orNte3nQ0w/cx5fi0PHRhlEf5YU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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