SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '647ed12fa257c3facd4ca697458b971d50f96fd03cc53dc23fbd17478648b152' 
  AND token = 'KxYUimvwrDLTM9BL1K84Uj0YIM0ic3RQOYGuIzFfQI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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