SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '337018070dbde5d52b1d08fc7b8b17c419371ddf06d3600e35f8d71b968b7770' 
  AND token = '6WKJFSdzQdJlrL6EK3kuuTRRKOI/24GonpcqFnxG8jM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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