SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6e4923b9d73ccf93cfdb91ddc643dc48ad36317dccf2346a81939257bd8a4e9' 
  AND token = 'hcmZu5KwyXwXQPORIKB0WaJk2SA2YBKzmE45VKRGpcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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