SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15341ec84ea77ede379198d5c90d39168ad88b4aaba68c31b566a813808fb555' 
  AND token = 'OTR7dAq2JnFzyRMJ2FQ3dbyK5QwVl+oLGI5AsI1eMk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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