SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f57fc72b21e752e4ca55fde2ff69cc41591d8c86c79911a17f33a2c34cfe568' 
  AND token = 'gKyrKwunRXlRf3vVcyeAGbdKGylOzffNt2BsBZIwvIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}