SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28e84206b98061f97098a63591ade8d3ca0c1f5e50cbbec09d9ad8a25a4143b3' 
  AND token = 'qNBxlL6Zm/OFcrDeVsqgckcSg4wFkefXjQPu6p9+rBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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