SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42b1014576cc8d5a1058505aeb393bbfb6e1dca3ddb6c9bf54a7a6bbdf1677ad' 
  AND token = 'JYgwoSU3WCLWU4cqs4SogFQjDB+BgbdkHuUk6cxmAYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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