SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c46c9871dfb543df9ebc8e3f7f08df479ec54bd76b4fec012317c9de6be2485' 
  AND token = 'GXpmYN/FkSf6vPhyW7EcQ+uktkDV+qTQp/IHxZrOXXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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