SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8968e01d004be6a94aa040381941e96e15fc2c37b6e5eca1c3d1c7f560ed39c4' 
  AND token = 'LB+YiizobOZA521+PnjT1sUfZGuXJ6S360gyNJje9Gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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