SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8f43af5b003a6ade046172ab8bed4726a35a857eaad11094246e48ba80ed34' 
  AND token = 'UC/QoSXv3n8K7cOwhrEhKGoBxkLf8Ob/sR+kdLRlqEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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