SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a400856467d77b7fe16779352c372d0fbf3e1715b4b89494b38e365739b61c9e' 
  AND token = 'ZFfgH6zYpZP3OJgn5oSmS/1lKxQK1SW6v9zOfyrv2R8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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