SELECT 
  b.*, 
  d.*, 
  c.* 
FROM 
  cscart_bm_blocks as b 
  LEFT JOIN cscart_bm_blocks_descriptions as d ON b.block_id = d.block_id 
  LEFT JOIN cscart_bm_blocks_content as c ON b.block_id = c.block_id 
  AND d.lang_code = c.lang_code 
WHERE 
  b.block_id = 52 
  AND d.lang_code = 'en' 
  AND b.company_id = 1 
  AND (
    (
      c.object_id = 288 
      AND c.object_type like 'products'
    ) 
    OR (
      c.object_id = 0 
      AND c.object_type like ''
    )
  ) 
ORDER BY 
  snapping_id DESC 
LIMIT 
  1

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "b",
          "access_type": "const",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["block_id"],
          "ref": ["const"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "d",
          "access_type": "const",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "10",
          "used_key_parts": ["block_id", "lang_code"],
          "ref": ["const", "const"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "c",
          "access_type": "ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["block_id"],
          "ref": ["const"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "c.block_id <=> 52 and c.lang_code = 'en' and (c.object_id = 288 and c.object_type like 'products' or c.object_id = 0 and c.object_type like '')"
        }
      }
    ]
  }
}

Result

block_id type properties company_id storefront_id lang_code name snapping_id object_id object_type content
52 products a:5:{s:8:"template";s:61:"addons/product_variations/blocks/products/variations_list.tpl";s:46:"product_variations.hide_add_to_wishlist_button";s:1:"N";s:23:"hide_add_to_cart_button";s:1:"N";s:36:"product_variations.show_product_code";s:1:"Y";s:44:"product_variations.show_variation_thumbnails";s:1:"Y";} 1 1 en Variations list 0 0 a:1:{s:5:"items";a:3:{s:7:"filling";s:37:"product_variations.variations_filling";s:5:"limit";s:3:"100";s:19:"variations_in_stock";s:1:"N";}}