SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35837016f65e065c55e6bd1d34615998fc04a212f94d20c9767649fe6f09279c' 
  AND token = 'i3Q11hYR5nQsloKN3QnSPc57uM/l8tN3oQFlnty/wK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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