SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e02d754b7a756625396c5a06cfd5fe2377c3b8debd13f703668f639062dad939' 
  AND token = 'KXrDdshJvTtVjmDFLZPyjLdyr/fzbzPA2ryKhk3+zGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}