SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c243b17c06992011a6d2752c865dc0f0f83d465b43a57e1d4ba422fc9269f63' 
  AND token = 'ztjHhCV6KP0TkL8oBCpchLwiMOjaMtFTyCM8qVE3oas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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