This is an irregular verb. It is a model verb.
PresentPresente
Yo busco mis llaves por toda la casa.
I am looking for my keys all over the house.
PreteritePretérito indefinido
Ayer buscamos un hotel barato en Madrid.
Yesterday we looked for a cheap hotel in Madrid.
ImperativeImperativo afirmativo
Hijo, busca tu abrigo, ya nos vamos.
Son, look for your coat, we are leaving.