SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5999d29063242a479fb39319d2ae4a569a0ee27ce4cdaab7882244afc820614' 
  AND token = 'U+3iudeQZ4BFKZJ5//YSHIFo9zQzsW8JE9iQFvwzTrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}