SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750b18bfb979d67e5359c793315fe8b6fa769e48899791c9b01b8f76ed12e5fe' 
  AND token = 'oQsd9+PfSRDE0431hhUxjPk7mSDzpYIXLNLjrAlsehk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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