SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6cbb10f44e1741122c715f486d5a1ea1d6cce3743a9f2f7eec89aaaf167dd54' 
  AND token = 'Upi9TSd6nLysdOM4W3meJEE8k764gqky5cNCGEDmiIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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