SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f9c1a8e43747be3e2f3836381de9da6ef9d9ede690dd645b32cc12410550aa6' 
  AND token = 'SfSDk+bstW9OlJC39SvfCrjZkLkhPZ7CXOQNMqzNbMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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