SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f83a5cf35ef96f9f80325c19d4035a47fc225773bbdc67a54c76c6eb306df404' 
  AND token = 'z4/HKXFjhkDviHeag6fYDJogHdifb+cz+T+DywNGxbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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