SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dad2047cfe9500278fc0d561610e3f5019e165b29dd7b69d0651134758b2ac62' 
  AND token = '2STjamnMlkwhSu6GETntVK1prN2fMv41V7bWKOh7B9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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