SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69b40f29b306d1a30768fcd97d607e5345aa463e221278a4f60ab5390f24dd10' 
  AND token = '6hZlEFON9SQLc/ke+xQNHndw8tBDCeMMmVGquwLzyI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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