SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f21a7b8d5607a886cbcf773c773987461debcec30ae66196ebb161b39769799' 
  AND token = 'IAs6vPnr2jUKbc5b0UAwQ0MVdwsL/vCevaEKTdXLuCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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