SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f6fd54cdbf465fc002788ca35fabbe7a7a7f256700f4fae1c153fbe0cadc241' 
  AND token = 'Nhy7L2iTnnUeEEObBR/AALexBqtYFxVDfj7ukOTcnSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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