Do the coronary arteries contain oxygen-rich blood?

No, the coronary arteries do not contain oxygen-rich blood. They supply oxygen-rich blood to the heart muscle itself, but the blood within them is deoxygenated.

The pulmonary arteries carry deoxygenated blood from the heart to the lungs, where it is oxygenated. The oxygenated blood then returns to the heart via the pulmonary veins. The aorta, the largest artery in the body, carries oxygenated blood from the heart to the rest of the body. The coronary arteries branch off from the aorta and supply the heart muscle with oxygen-rich blood.