SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3ed5767df72d0d485add7bae91cfbc8e1e17b1a7d66feb404112fa61e278e26' 
  AND token = 'CfgaxFL+TJGJbPjVFyOlRQpINzshiDsdhfVLzLa0qEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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