SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da4c1b64a4a678731e169c1285a4ec4b55b46b3ad76514b1d395075faf05b538' 
  AND token = 'tX5+twA9+NGlKnbGRctb5LmbPPIQOAsaohtGIIItXoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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