SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9de3ba5ae4f1bc609ee59edf94fd12864bda85cb7644bcb6bc9cfd946575928' 
  AND token = 'txwIhyaim92iPYuoTlePoqBNemtFhoiovxCAz8rhL28=' 
  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"
    }
  }
}