SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88681f992ba0f6a29e4dc125f4fc76f070d011145f93d7da94f6455795ab38a3' 
  AND token = 'he9RkADyjwz9VnGUJ6+BNNhxdoIMb5YBwMpxh/IWWvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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