SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ce48c1a5a8250ea1d9bfb3f41beebe1f302bd7dd336e92d40d2f745836ca25a' 
  AND token = '50JDqOKKP89+iKlRAi5/wuNxzRHAjsmfU+nEmEWnkZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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