SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0362b9e795bf1bef73cc52d165270575f68a9310dcaefac103e096c12f5f0412' 
  AND token = '9cElfopj5sTGlHAH7WRFA0buVUdpLipRfZuwhbhKBgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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