SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41e7bffe58bb0d938be204f532d5512c3a7e92d0a2df05ac47aa7676b9affa36' 
  AND token = '4+tG7Di92b1rSCKpFJCArKRVtcwbqZYhoiw5nOvl4jE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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