SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fc8dbe1b32ad0c770c906aa942bf22a879016c242d3dc7689da4dbeb4b0e765' 
  AND token = 'L4d6E+x7bFDJfzzoGHU9EuEgdRjD9ALnLQvFfW4iPzA=' 
  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"
    }
  }
}