SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28308320742e7ff0e3ce833d86875b1d1a2a35cc8c7e6f135520a9e2cfe18d2c' 
  AND token = 'uDymJOyQqCyUDkbYk2WdlT0uzd2sQu0zh3p8i2CAuog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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