SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a17140c78a44349fe97fd92605e0fcba8085ccfaba7134e33b9c11789bf0542' 
  AND token = 'urFzy12Tfjj/diP25GFXjexyGhePOJG3mt41ZowB860=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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