SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'ff7f71e668f535591bf7a750a7f0785af69ab245efdb3b7fe392b85918ce41f6' 
  AND token = 'Hdn//ur8FzhtvOXLXlt4bq+hewv2eWwcumWFAUYRmbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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