SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef590a7f96c71461d053045dbc23957391825a073afe86b271f0f4014c23c664' 
  AND token = 'ZBx8m+L/6Z5rPefU8g6K8IMtOsPV85h2kKpKATd2IWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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