SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84cf2e7d941d7b698deb66ee0b5469c0d144c5c93a353f511d5979735970aa64' 
  AND token = 'HUfO1IqN6dbf+pbC7v5PFHQ2FR/QvYXxpKZFC5mxh/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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