SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f18dfa74001f1a25568f0802f48718235ec15a5e19b1b43ec3d9784dcf36a38d' 
  AND token = 'lEuGUfr7F5mkjjB9cU7XAovyocKXXnCXJNQXaLbHbzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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