SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b507148cd3efb32969216649baa853c602bb4d7c21a49fd81db32fe0b9889e4b' 
  AND token = 'df4KJ39Ub+vysEr2WXF5djet5BrYdLoHfNNAp8I4KB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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