SELECT 
  COUNT(
    DISTINCT(cscart_companies.company_id)
  ) 
FROM 
  cscart_companies 
  LEFT JOIN cscart_company_descriptions as company_descr ON company_descr.company_id = cscart_companies.company_id 
  AND company_descr.lang_code = 'en' 
  LEFT JOIN cscart_company_descriptions ON cscart_company_descriptions.company_id = cscart_companies.company_id 
  AND cscart_company_descriptions.lang_code = 'en' 
  LEFT JOIN cscart_absolute_rating AS absolute_rating ON absolute_rating.object_id = cscart_companies.company_id 
  AND absolute_rating.object_type = 'company' 
  LEFT JOIN cscart_vendor_plan_descriptions ON cscart_companies.plan_id = cscart_vendor_plan_descriptions.plan_id 
  AND cscart_vendor_plan_descriptions.lang_code = 'en' 
  LEFT JOIN cscart_seo_names ON cscart_seo_names.object_id = cscart_companies.company_id 
  AND cscart_seo_names.type = 'm' 
  AND cscart_seo_names.dispatch = '' 
  AND cscart_seo_names.lang_code = 'en' 
  LEFT JOIN cscart_discussion ON cscart_discussion.object_id = cscart_companies.company_id 
  AND cscart_discussion.object_type = 'M' 
  LEFT JOIN cscart_discussion_posts ON cscart_discussion_posts.thread_id = cscart_discussion.thread_id 
  AND cscart_discussion_posts.status = 'A' 
  LEFT JOIN cscart_discussion_rating ON cscart_discussion.thread_id = cscart_discussion_rating.thread_id 
  AND cscart_discussion_rating.post_id = cscart_discussion_posts.post_id 
WHERE 
  1 
  AND cscart_companies.status = 'A'

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "absolute_rating",
      "access_type": "system",
      "possible_keys": ["PRIMARY"],
      "rows": 0,
      "filtered": 0,
      "const_row_not_found": true
    },
    "table": {
      "table_name": "cscart_companies",
      "access_type": "ALL",
      "rows": 2,
      "filtered": 100,
      "attached_condition": "cscart_companies.`status` = 'A'"
    },
    "table": {
      "table_name": "cscart_seo_names",
      "access_type": "ref",
      "possible_keys": ["PRIMARY", "dispatch"],
      "key": "PRIMARY",
      "key_length": "206",
      "used_key_parts": ["object_id", "type", "dispatch", "lang_code"],
      "ref": [
        "fluentmart_cscart.cscart_companies.company_id",
        "const",
        "const",
        "const"
      ],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_seo_names.object_id = cscart_companies.company_id and cscart_seo_names.`type` = 'm' and cscart_seo_names.dispatch = '' and cscart_seo_names.lang_code = 'en')",
      "using_index": true
    },
    "table": {
      "table_name": "cscart_discussion",
      "access_type": "eq_ref",
      "possible_keys": ["object_id"],
      "key": "object_id",
      "key_length": "6",
      "used_key_parts": ["object_id", "object_type"],
      "ref": ["fluentmart_cscart.cscart_companies.company_id", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_discussion.object_id = cscart_companies.company_id and cscart_discussion.object_type = 'M')"
    },
    "block-nl-join": {
      "table": {
        "table_name": "cscart_discussion_posts",
        "access_type": "ALL",
        "possible_keys": ["thread_id", "thread_id_2"],
        "rows": 4,
        "filtered": 100,
        "attached_condition": "cscart_discussion_posts.`status` = 'A'"
      },
      "buffer_type": "flat",
      "buffer_size": "2Kb",
      "join_type": "BNL",
      "attached_condition": "trigcond(cscart_discussion_posts.thread_id = cscart_discussion.thread_id and cscart_discussion_posts.`status` = 'A')"
    }
  }
}