SELECT 
  cscart_bm_snapping.grid_id as grid_id, 
  cscart_bm_snapping.block_id as block_id, 
  IFNULL(
    dynamic_object_content.content, 
    default_content.content
  ) as content, 
  IFNULL(
    dynamic_object_content.object_id, 
    default_content.object_id
  ) AS object_id, 
  IFNULL(
    dynamic_object_content.object_type, 
    default_content.object_type
  ) AS object_type, 
  cscart_bm_block_statuses.object_ids as object_ids, 
  cscart_bm_snapping.*, 
  cscart_bm_blocks.*, 
  cscart_bm_blocks_descriptions.*, 
  cscart_bm_block_statuses.extra_object_ids as extra_object_ids 
FROM 
  cscart_bm_snapping 
  LEFT JOIN cscart_bm_blocks ON cscart_bm_blocks.block_id = cscart_bm_snapping.block_id 
  LEFT JOIN cscart_bm_block_statuses ON cscart_bm_snapping.snapping_id = cscart_bm_block_statuses.snapping_id 
  AND cscart_bm_block_statuses.object_type LIKE '' 
  LEFT JOIN cscart_bm_blocks_descriptions ON cscart_bm_blocks.block_id = cscart_bm_blocks_descriptions.block_id 
  LEFT JOIN cscart_bm_blocks_content AS default_content ON cscart_bm_blocks.block_id = default_content.block_id 
  AND cscart_bm_blocks_descriptions.lang_code = default_content.lang_code 
  AND default_content.snapping_id = 0 
  AND default_content.object_id = 0 
  AND default_content.object_type like '' 
  LEFT JOIN cscart_bm_blocks_content AS dynamic_object_content ON cscart_bm_blocks.block_id = dynamic_object_content.block_id 
  AND cscart_bm_blocks_descriptions.lang_code = dynamic_object_content.lang_code 
  AND dynamic_object_content.object_id = 0 
  AND dynamic_object_content.object_type like '' 
WHERE 
  cscart_bm_snapping.grid_id IN (
    6628, 6629, 6630, 6631, 6634, 8945, 6632, 
    6633, 8944, 6968, 6969, 6970, 6971, 
    6972, 6977, 6975, 6978, 6979, 6980, 
    6981, 6976, 6974, 6973
  ) 
  AND cscart_bm_blocks_descriptions.lang_code = 'ru' 
ORDER BY 
  cscart_bm_snapping.order, 
  cscart_bm_snapping.block_id

Query time 0.00210

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_bm_snapping.`order`, cscart_bm_snapping.block_id",
        "table": {
          "table_name": "cscart_bm_snapping",
          "access_type": "range",
          "possible_keys": ["grid_id"],
          "key": "grid_id",
          "key_length": "4",
          "used_key_parts": ["grid_id"],
          "rows": 38,
          "filtered": 100,
          "index_condition": "cscart_bm_snapping.grid_id in (6628,6629,6630,6631,6634,8945,6632,6633,8944,6968,6969,6970,6971,6972,6977,6975,6978,6979,6980,6981,6976,6974,6973)"
        }
      }
    },
    "table": {
      "table_name": "cscart_bm_block_statuses",
      "access_type": "ref",
      "possible_keys": ["snapping_id"],
      "key": "snapping_id",
      "key_length": "4",
      "used_key_parts": ["snapping_id"],
      "ref": ["devmotorsbay.cscart_bm_snapping.snapping_id"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_bm_snapping.snapping_id = cscart_bm_block_statuses.snapping_id and cscart_bm_block_statuses.object_type like '')"
    },
    "table": {
      "table_name": "cscart_bm_blocks",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "4",
      "used_key_parts": ["block_id"],
      "ref": ["devmotorsbay.cscart_bm_snapping.block_id"],
      "rows": 1,
      "filtered": 100
    },
    "table": {
      "table_name": "cscart_bm_blocks_descriptions",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "10",
      "used_key_parts": ["block_id", "lang_code"],
      "ref": ["devmotorsbay.cscart_bm_snapping.block_id", "const"],
      "rows": 1,
      "filtered": 100,
      "index_condition": "cscart_bm_blocks_descriptions.lang_code = 'ru'"
    },
    "table": {
      "table_name": "default_content",
      "access_type": "ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "18",
      "used_key_parts": ["block_id", "snapping_id", "lang_code", "object_id"],
      "ref": [
        "devmotorsbay.cscart_bm_snapping.block_id",
        "const",
        "devmotorsbay.cscart_bm_blocks_descriptions.lang_code",
        "const"
      ],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(default_content.object_type like '')"
    },
    "table": {
      "table_name": "dynamic_object_content",
      "access_type": "ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "4",
      "used_key_parts": ["block_id"],
      "ref": ["devmotorsbay.cscart_bm_snapping.block_id"],
      "rows": 17,
      "filtered": 100,
      "attached_condition": "trigcond(dynamic_object_content.lang_code = cscart_bm_blocks_descriptions.lang_code and dynamic_object_content.object_id = 0 and dynamic_object_content.object_type like '')"
    }
  }
}