SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f751c364e0f23c5fe5e66fca86718a0d7cc680276c0b3b8397737351a709b4a2' 
  AND token = 'uiDt9UKFaZl4AA+IYbivUJfnv5s/dR+bXZNDaNX4wBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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