SELECT 
  COUNT(*) 
FROM 
  cscart_states 
WHERE 
  country_code = 'AU' 
  AND code = '72' 
  AND status = 'A'

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}