SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91959cceb432d7d62c635fdea6a31848b6f2722aeb20b9a5e3d908eee6d72743' 
  AND token = 'UCtHz4BZNmJnNY1yhOt8hNzTDop/gDl77mDMUHxw4L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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