SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '938ba7f2be8ef471852f09b1a81362570c8f661a15063843ed2684c2b03256c6' 
  AND token = 'iWdTGEtoBDAMVsVOlnpUsYfQMvDgQWMkHoPRqbAqJDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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