SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db8a480284609f7c46041b11ef45b1d4baf11d1b5f986701335347fa1d5e300f' 
  AND token = 'x+bopISK/qDyxK9KI+v9yxBxmYUqwtAo+Mw7puhmkVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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