SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c57612aa2021af8b12ac7b2b43e5723b1c58d9595a2ef60906dfba7d47588ed' 
  AND token = 'gQ7wg/q0WQqFFsmYg1cXEVHVm/gX/jPSeGDgb+/W5T0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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