SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c3a86883e8443f65169bbeefbc81277e4db6c90b835146feeca14256a59f840' 
  AND token = 'LNTjGJ7xKhSSuKZ4hxASH0eJQ5sQm++Jqkcn8aMazaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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