SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84ea74bcf36ef9647f84b28fb693d4e1155ccafe6dee897474f376dc175bebe8' 
  AND token = '9ROJOSiTbUWlNQkwcTrdJCM1XmIl+lAZRX4y82jHgkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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