SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da78209238188e35cb2492942caf7360f8f124d0a9eae95db68be34c9b27bd84' 
  AND token = 'AfR3xmpOQ43ONBbmj0pIMttTkEgJOHLTF1RTH0oMG4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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