SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6739f3156ca3e71df45c9b2d2c361a2658f16b8b07735bd639cee9844ae2dae' 
  AND token = 'iTs4XxVwMLClwsf5gQJ7hDZhc8zvsBxx9RssTyXarp4=' 
  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"
    }
  }
}