SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50da532d8beb27a98b33a87c63d1637cb5e115eaf1c00c4d93bd5585863072f8' 
  AND token = 'hdtlZW6D2A+IyvdYAWWgLUjFvPIqj+gdbdZYKUnq8wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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