SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35df52f30f3b876cb1dbe0e9100c847dae6dc917b3c69e734901ffad4c9d8c47' 
  AND token = 'SWV6gyuLrwBnhCShAT/W8lyvUsGTp+cZEzzJ2EAYLfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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