SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339979b17c4559e45cd61836175fed84dcb6d4e626e20013333133e733a0e3ce' 
  AND token = 'THNx01FNRXLQYHX86qOgUfbptRv8/+Vjo+mh4c63Etc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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