SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7b53ede2e2f27f80e52a0617faf5eb920b55a11f3dd28be2b4a91bfb8be9121' 
  AND token = '/7nOYfurRvAZjOOLu/NB3t9IRW0NoEnizJcYureO8pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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