SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5be502f052a7a729765559a4627aba1110fb6480fdbad7c844a644d4c441bf3d' 
  AND token = 'LcRzfONPrzd1eHd5M+Qi9guLr6ZwzNWxvZxG47eUXAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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