SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6861d19100c7536cfe77bee8a732ffd34fd445fe13428c78879999b405ea2739' 
  AND token = 'QrjsC548r9NnMhcFi6CWfZpWNAykkiW/ujZQLTbnlFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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