SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ef50048c0a588bee12eae98208345901556e55863d426a44e2a5eb40256380a' 
  AND token = 'C6gF6akJuDQ2h/7YtZndENEwe9tG0Kiy400AJSmnoQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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