SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'cb5cce0cbff4b6b49981a21834d238df323a96cb0c0080d835fc8efd55291f83' 
  AND token = '0ctMoVzwLoa5AUPm+dMGMhldJ1OiQB3BM00GxXssNqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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