SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb293a5d887714c41851e7f63471dcae47ecdb8512aedde3c86214e94e8046a3' 
  AND token = 'pjwguYacFrGTGDbr3aXxAgQb2JTlOmk37Qo5/+AypWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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