SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '652f87040e6926d842d23e7def3c2d86a09cbeabdc67825710ffaccb223ade2f' 
  AND token = '8RsPkUTXVZP/JcmOR6KTRz2ZqHwgO1FBnvRDjyIIV5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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