SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b73590589725836bec4effa05c25a908486b5a9d4dce92da6aee2f7946569fc' 
  AND token = 'sKhKalUvAfymVtos2iz3ogWGblVb+LOD8Yeyho6YYDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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