SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8b4c4a96dde2101725d9475cd6005a61077574762e71a15e126b48218d71d62' 
  AND token = 'XgUcxNVhtNqRzrLqO990FxbOa3okQlYXADKLzlHPACc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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