SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3202df586ead473c5b2bef04257472e9176417b616fdcc3ec682083bae66638' 
  AND token = 'IkUmBYrRBZso/VBmlsukBkfXQcP0vzvhWo9KiJeWHDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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