SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31714918e9cc3a4b2d32aed7ceebe0782b01a4af1b4f7d70c5310a836c9a07b0' 
  AND token = 'pEWzKsgTdN1qirqL5UyTFbgOkj0ROfLwCn9DCDaztBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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