SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '686364be36d1c42ca8d1367d14c6bd20e00277d46cefd2f6a1c2cb868ffd59fb' 
  AND token = 'jvJ5nGllBsGp03Zm+PgO10sbFLBYPa1yckExYKz1rkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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