SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82712ae8f921be464d5988eb3e667d2412bf12a1fd602d46d3e4beeda5f41d97' 
  AND token = 'aZzfDBdV6JiQPNjpq8DaeWC/XNOeilL3r5sdkPhL3Ko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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