SELECT 
  COUNT(products.product_id) 
FROM 
  cscart_products AS products 
  INNER JOIN cscart_companies AS company ON products.company_id = company.company_id 
WHERE 
  products.master_product_id = 804 
  AND products.status IN ('A', 'H') 
  AND products.amount > 0 
  AND company.status IN ('A')

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.007713046,
    "nested_loop": [
      {
        "table": {
          "table_name": "products",
          "access_type": "ref",
          "possible_keys": ["status", "idx_master_product_id"],
          "key": "idx_master_product_id",
          "key_length": "4",
          "used_key_parts": ["master_product_id"],
          "ref": ["const"],
          "loops": 1,
          "rows": 2,
          "cost": 0.0052712,
          "filtered": 71.24736023,
          "attached_condition": "products.`status` in ('A','H') and products.amount > 0"
        }
      },
      {
        "table": {
          "table_name": "company",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["company_id"],
          "ref": ["u428615623_ecartifygonje.products.company_id"],
          "loops": 1.424947146,
          "rows": 1,
          "cost": 0.002441846,
          "filtered": 100,
          "attached_condition": "company.`status` = 'A'"
        }
      }
    ]
  }
}