SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df816a216c985123635b491f0918098c7d8355b48d85eda6e73f806fa01daab5' 
  AND token = 'fQAgmNsj78LBC6B2r4EmOWFcDqBhnLurEK6F+B/Q/PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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