SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28276fc95f76bad113218ee6d531151a710d7e7b571e89e9ee5644731558aaa7' 
  AND token = '19t44ZotjY7TVHJETfGD5DUBMvYwubDjjHiYLAZs3MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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