SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d842b88692f6d8ef67487ef9ec99b5b89e9706631534b5add888a97f54c6a91' 
  AND token = 'SUdZ/6sjRQrARZpnJCqXqPQqNbZbmm8bmMRF2T6onFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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