SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '640ca57f5506b8b95d731935248da96b942b1699cc0fca0bc551f20817e6ce94' 
  AND token = 'OazT5rqEzLOHJnJE5FPtao0pQ823/WZa/8jJ9Ub+gW4=' 
  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"
    }
  }
}