SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '435c5b16c3b3878cec956ffb324f5c62fb49d626acf0a13dc1352c9ca5aae477' 
  AND token = 'iULC9LUVH8BUfyXnweCfZjAQo/XU7g+mCHvyW2fMvyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}