SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c42fd74b61aeddccde350d7c661823cd8ae4196cd50a6dbb6a73e9390798fc91' 
  AND token = 'KQGwCQL7JHhHq8/CwpRFUMMv3FVh0XxdbrsPDXg3sn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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