SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3861dae76d6e68ea509fd60d6cde94574316f1770116a66d77546173dce7c3c' 
  AND token = '8vonX3IUiiGdl9RkVPacdp80WlL/ew5jZneMZOX4HI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}