SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98c209039d40ff521f055a625dba7fee53dcb471b1b943e4afbf49911929a09a' 
  AND token = 'q/Wjk4L+7v/6ZzkWQjBX6tukeHZCJl/Y04CbgFOvcbo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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