SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1d36f1ccc25aa43038b9e71595fa39e04b9457aa571acd5a4ef9ccb3f3a660e' 
  AND token = 'Mxw+J0BdB3mE7Xu8dxTcU8/VL0GqHsYN5tSQH9hsTDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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