SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3b20635b350a93178c5bf2deac8a65d479dea3bf0de37c2a02e221b8ed80f3be' 
  AND token = 'Z/XZh1nzf5wod5gN3BuDD7RtF+TAGmH1OCJxMQIBS90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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