SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78e5d04a69c369079e1c7d6cac3986950faa998616fd7fe42f532335478d5021' 
  AND token = 'Vs2WUzciO/voq5YIr+HJpm8o7agm7Xi6MgPZsbQPvLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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