SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7e01c93426ffad0889b253567194536154bcbc0b335f66dccc9ba96c538e042' 
  AND token = '1mAW0jeghxqg8hoGv42VlQ34LefWpYBWduYhKtezPAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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