SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a7bb3d00b88203887fc4973b3b5fc315e8755a2942aba9c5a9a3a7fd5a4b280' 
  AND token = 'BhlBzzqktvpVZE5Znm17itQ1tR/PR+Jxp7TDkAD6wdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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