SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ee4dfbb586270fe6820eda97c92c7f0c6eb1fcb55e7e2d5b4fb1435e55296e73' 
  AND token = '/GRjNi8PYpMhr2VqeHmYjYmv+c0kyYEIMZIzCAsr8ag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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