SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4da6820dc4520d6f495601e2c96961c53f1c73dd51838f7abcae45bdff6c9049' 
  AND token = 'j9ukrjyOAmgg6mLilPSZV7Z+YnNy+ngDBKnbG7/MDUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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