SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4d315b57cbb7c49786cfe074a98dcf5b3396327fa2b623420b8655c7076e7b1c' 
  AND token = 'PHfW+NVzRukyuHFzYaO6XFnvF/d/C9fvKOoOxL8G5d4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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