SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfb45a7f0e94e0638871468427f8c6d7bb4f729e09f736163c256af33b921cb0' 
  AND token = '6YbZxOEWBNsszH6Knn/0wzNuUdQGJ5d+AUKyxSGYe/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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