SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8ee5a9ceba5b38305390ae5a5a8aef553e12d156329dfc85240572ab7dc0b1cc' 
  AND token = 'X8tAAF8+cBbghSOrhwjrU3uozab4uob9I/BmcaP5PCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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