SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c7b987ceb055ae907656adc9292051346a6b3ce3c0ff7cfada8334975bd323c' 
  AND token = 'DxJUaL7jqlN6gdVMnfRkkJbFUF9QWwKEpZwDfwPR6ko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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