SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfb6398766d98ce80639a5f89d7cab3552ef9288937f610e909ca06e3ae0eaba' 
  AND token = '1xQVQjGOHUhMQ+6SPjWMf39VZPy2nbiD025738Wjm3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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