SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f9dcd3b378d56859f313090673f3f635029e593dc8644bd80bcacdc1af7e947' 
  AND token = 'zsG/Q1Z4657vKRUWjW2FYPTEZ5QLDxpqP5MfsOc2EDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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