SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3326436c329adcdc54b50cbdd56645d1fcf3a8fd279cb7081a3e08362beb69f4' 
  AND token = 'XpYE9ydxFGKB9OpOEHwfqSiQM8oypAvXwB3x2VDlwzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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