SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24ec8bd258faf98ceb5d4f17763fd65ac149d4ec67caf5a525b7b92c9a1f8879' 
  AND token = '+11xbMcuxeoDK2ai/qZUg0+Lt1gv3Kpe0vjSH4QhGKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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