SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52def43cbbe3c955833209e1b73c0410583ad61b843ab4e1504455ee8b246ec3' 
  AND token = '8udmXhgkpZA8SWvW0ziSPwnNqSnhPihptB1n7PrJ7fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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