SELECT 
  var, 
  value 
FROM 
  cscart_ab__so_noindex_tech_pages 
WHERE 
  object_id = 313 
  AND object_type = 'category' 
  AND company_id = 0

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_ab__so_noindex_tech_pages",
      "access_type": "ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "68",
      "used_key_parts": ["object_id", "company_id", "object_type"],
      "ref": ["const", "const", "const"],
      "rows": 2,
      "filtered": 100,
      "attached_condition": "cscart_ab__so_noindex_tech_pages.object_type = 'category'"
    }
  }
}