SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a840ff9d8b38c5b3cd5e3ae2e05f2aed803b5f88e860257d939f350734abec1b' 
  AND token = '4dXUJ1Ypu/fyHO5+IPohUdkGzrIXTvOKVzykXAwlG4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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