SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b6132ec29c5d25493994f5edd4503c87879c6618dffae8f8bcbd701498569a7' 
  AND token = '0JYo5OzkshLdzL9z8QKaE+etFgI770BEN7KdMWS0geE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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