SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e993198f59fe7c0c2edcdf235690572667359849e994ec4982501e08378235b' 
  AND token = '0HoHDR4DzbvC7DRoYIp2ASCvWLeLvwNu0q/rer549ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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