SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1fd387aac47c221ffa2a716ce9cf4dfaff84d23b64878d988503f40270d0560' 
  AND token = 'VokOUI3RM6kVzPQQolJrC/lztjXBG4KkgZ4kfpr24F8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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