SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4356c51bc128aabafab7225903996450b555368c1e69bec3bbfb7aeb58ed6c30' 
  AND token = '6dZcnjT64h/xRWbRKAQGVEYM3SCJhWz+SQZcMsqRYAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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