SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '532eaaa5871108689f24a81716a72098260a77240d927800c0ac4a81a9f656af' 
  AND token = 'px3If/5hRhEdt9hEWCQhaQtbO4bAeaHW98RNSyk1QJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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