SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c261ce8f7624bd4883778c834c14d74843d31d6a8a87eee80e78281c2681e964' 
  AND token = 'lqL6oPZQsr9vIboPEmmOB/DpAdnED+qC07/UxxzrNRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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