SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d8ccd9a2804eb0b4526ab0b7df4bec19497590f409be9435a25dcbc6c80a478' 
  AND token = 'u8AkqdHhsm1tQ4UGZ4DBMJ9YcCvvPdfwDz2WLoRTsHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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