SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02da6352ca39f7ce1b8bf3717f85d3423b197536331c141599385975b6819029' 
  AND token = '2GMRy2dnR7c7qzw/XkUefOHt4mzD+LL56g8szukDTKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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