SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38e807c815fce7f175b9ddb156c81a9895781a3af012e6f805fcb2d61b487c17' 
  AND token = 'U6jDgdqaZcll7APSo9/wDVrwBv37KrNoDj41pbGgGqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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