SELECT 
  cscart_users.user_id AS user_id, 
  cscart_users.helpdesk_user_id AS helpdesk_user_id, 
  cscart_users.user_login AS user_login, 
  cscart_users.company_id AS company_id, 
  cscart_users.firstname AS firstname, 
  cscart_users.lastname AS lastname, 
  cscart_users.email AS email, 
  cscart_users.user_type AS user_type, 
  cscart_users.password_change_timestamp AS password_change_timestamp, 
  pfd.value as nickname, 
  CONCAT_WS(
    " ", 
    IF(
      LENGTH(`firstname`), 
      `firstname`, 
      NULL
    ), 
    IF(
      LENGTH(`lastname`), 
      `lastname`, 
      NULL
    )
  ) as name, 
  mute.status AS user_mute_status, 
  mute.set AS user_mute_set, 
  mute.seconds AS user_mute_seconds, 
  company.company AS company_name, 
  company.status AS company_status 
FROM 
  cscart_users 
  LEFT JOIN cscart_profile_fields AS pf ON pf.field_name = "nickname" 
  Left JOIN cscart_profile_fields_data AS pfd ON pfd.field_id = pf.field_id 
  AND pfd.object_id = 82 
  AND pfd.object_type = 'U' 
  LEFT JOIN cscart_chat_mutes as mute ON cscart_users.user_id = mute.user_id 
  LEFT JOIN cscart_companies AS company ON cscart_users.company_id = company.company_id 
WHERE 
  cscart_users.user_id = 82 
  AND cscart_users.status = 'A'

Query time 0.00184

JSON explain

{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "table": {
      "table_name": "cscart_users",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["user_id"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100
    },
    "table": {
      "table_name": "pf",
      "access_type": "ref",
      "possible_keys": ["field_name"],
      "key": "field_name",
      "key_length": "98",
      "used_key_parts": ["field_name"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(pf.field_name = 'nickname')"
    },
    "table": {
      "table_name": "pfd",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["object_id", "object_type", "field_id"],
      "ref": ["const", "const", "dev.pf.field_id"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(pfd.object_type = 'U' and trigcond(pf.field_id is not null))"
    },
    "table": {
      "table_name": "mute",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "4",
      "used_key_parts": ["user_id"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100
    },
    "table": {
      "table_name": "company",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "4",
      "used_key_parts": ["company_id"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100
    }
  }
}