SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198b56a51f1963b7a7b722ef83aed99da3ed627cc28d0f9f727f976ccfea6d50' 
  AND token = 'QgWXgtE/hedR3qJiVdm+G3JKw19YG/iw/a/V0BxXCTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}