SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cef8bf0f23c64de669045ac65bfee683f318dc926b10aafbce4223492638418a' 
  AND token = 'o6E/00eDfADGB/xT0b9uFf2CRi7wV5Ox4PyLtmECRWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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