SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fef3a9357aff80d472d6fbf23028b30b1a6500aee40210123d0ea1666e5e726' 
  AND token = '9qZhMpYG9IajNhMuczWi0gFDJhPk/TkHqZrG36WDDJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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