SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '260e498a5c88f0618afa5d8a8d66941e45d9be09e940f29a6d126a828a90df47' 
  AND token = 'YA4GHsxczBzLfI0Imo4qQVneFRBSI03iOea+c+RiKrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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