SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8661a48d4b893ea0fa78c9ade8fde3064a4f45667783668206c20bb93ce88ba1' 
  AND token = '0jybQe2BcmMraToUzPINHfz5Jci479HczFoPWeUy6Ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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