SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bc298051872f626f1d14f1d0b6d37a214370bccfe33261555e952d05b64da06' 
  AND token = 'y/Sat42LBZkXaqfRWGqQB7UHEhUhw4EudJZhECMAvpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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