SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '643f31feab2031ea351952dca618693667effcd35c51b39c53bb522f2e938fc7' 
  AND token = 'sbyBnnjZCqLHm9FAnbcVIZ1tit447m3voD3TgCKzCkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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