SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8943e2bdd8ecadc0442448eb334b46bd15d80a8885775ed600b0a769b904db2e' 
  AND token = 'QxNLJjaHnhkKsHtzbFxpO5ZYMsF3WAtxF9T+4/G3HnE=' 
  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"
    }
  }
}