SELECT 
  tax_id, 
  address_type, 
  priority, 
  price_includes_tax, 
  regnumber 
FROM 
  cscart_taxes 
WHERE 
  tax_id IN (6) 
  AND status = 'A' 
ORDER BY 
  priority

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_taxes",
          "access_type": "const",
          "possible_keys": ["PRIMARY", "c_status"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["tax_id"],
          "ref": ["const"],
          "rows": 1,
          "filtered": 100
        }
      }
    ]
  }
}