SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c231bedf2471a4ea0268995b136f8d38cbb7509dceaa68d1eef7e9e2afa2899f' 
  AND token = 'oqMwKPmSXaKZAjPets/NBIEhXsKBjgH+wL01pbOrzjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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