SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '62a2494e2efd2ffd14e46cee11841645dd1fa44b460e4bd61158b275b8a33d07' 
  AND token = '/LK3jqroZj8blE72ErZXvqoh+AgcBKW9fRSJ5kFEW0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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