SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ad55dbb802a788471bc9c286237e99121cacf31ad4e68bff9ace663a932221b' 
  AND token = 'zQhXMo9S1b2Jtbet7ZOTCbJ8OHiOIqNMbJBgtBKnARw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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