SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b50ab0b0da1c4e4dad38ffba3cc57286e285d853205f6cc16fb40d4a944e2fb' 
  AND token = 'sJhLhMsGgth8StsRDgOBwTwTzXcR0mkN88nXmCcVTxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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