SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a13bdcf78e6b707f10302a09855801ea25a643d7450070a100675481cbc3a7e' 
  AND token = '1+RXzmNQd9rdz9eRVgExv01xtBoKQOJNHReJFgXUKvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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