SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a2b0badb79a0af1bed383429d58f9f2a7d313a874ecbd33d246c742a377b06e' 
  AND token = 'KmZ7Bf6HfXnzqTxz/gywH6GH6P4xTvYnj4nqbwGtQqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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