SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48672994dbae1774d749942fb7a366489882e7014d84d669f2acf2cb64f72f18' 
  AND token = 'fZT6RKQKrHQAKxV7euUKUUTCSVvv6w6QrLpIHbLmAYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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