SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291e79fcd3004b186cca1c92a867c8814c103e3ea816fba7e51a63e8648013d9' 
  AND token = 'eGNPpZMr3oiet+kRA/TEFKOv91ECnGX3U9ekACf2RWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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