SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b3c37f53cc20db03a28d9bc75788d9c9d0f3c39a6075449668121e68291a3eb5' 
  AND token = 'uA/kvjQEtMc8xc/0Swe3g/VHehJSyNSZYdMLczVtHJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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