SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49083bac0009c68172a6cffea2313305d410a79b8171b904dcf889f3e500e439' 
  AND token = 'gj3clczEXbDq9oSXxD/puRjGiRVbz4sJhpIUZ230FC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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