SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d910a77b4681e512a374b2a451d7e33628cb780a86046d73466bfba4f068f6c' 
  AND token = 'uj46gysfvo+L2VyDJ9yRDTSDdoQZyliMnjhUAvIeQrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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