SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd6dae3831364ace844345dca875476a956b1d724a627ba88f672e8f03e7a87a' 
  AND token = 'ibq/HRjEF0U3ZJk/SrsBmAQ0d3TlExI+MkrY1RB4+zY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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