SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '185d41b8dda445708aed3341738cab32ff6878cdba3c8a07a5b731a47f556bf3' 
  AND token = 'dQwUnLrlLVhECBfM+IThcwJRD+CZXs+nfzuO8IZI/pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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