SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f7b16b0b8647036704d88618d44d5acad58ab278fead4af017a04a5907202cd' 
  AND token = 'jfGafLqPXBXoUGCNz+kfGA+JSP7b7UC+OfTtZs/vBaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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