SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9390795c17012b12d4522ba2a4717b8947e8a9cdd569df6b3411eb577a28f71' 
  AND token = 'ihyCNn9MuOGr9wZbi+N99PnJ1gFaztaNPU+bTopwohQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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