SELECT 
  `sg_vector` 
FROM 
  cscart_sg_product_embeddings 
WHERE 
  product_id = 2923 
  AND lang_code = 'en'

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}