SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8a6051e7d47bd0a345a54d216e3287696520dd7220b65067bd07c62417ac32c' 
  AND token = '8BzAjQ6HByUWCnbTBdDudnIpnWLPeAd7WBIqWxanWTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}