SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cb8ab103020c3336c3c4c517aaefc7f0aec96e4ebd2023f8424634314938465' 
  AND token = 'm8vMvDKgyJYHXcBG7mw5NC6uSGud1FLXuiPD/PikQAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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