SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4dff7d3a46722d6c09a091cc6c4bcb2509977a6856c6d8052aa57474f7d6a21' 
  AND token = 'jhHBy/2/xOvpfGue8IIhhOaw/Fa6HlCt+ghLz5UB3NY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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