SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39674f7a2eba8f3619ef1bed649102e5ed9093567084c266e8ce335408c60464' 
  AND token = '0OxJktF/DxEnlKKoULuzigeonMZgVDLRKCfs/pyybLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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