SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7af9c0a58a0b671e55a7c5fe3f78147a3f6e5d3baad78992e4f2c81407f1228f' 
  AND token = 'LxHgC8H8YHuxL0v2UI/okCNXlpAnuQHec5aaLjYM4T8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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