SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b78a7bf2d08850d27879b117451376a9e42f425561f6a5643e957c3f57b60f5' 
  AND token = 'F3DflrW10Zd81E9yswZC3ZHaEo1h8SD4PoL6T/WXDJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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