SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec4b632cea2cb5786cc01c8c541afee20a6d567acd09a896e305a795bb478efa' 
  AND token = 'cwBYL1rFC2jawf1Re8wuuT2bET5/LDJso3+uBw7oDuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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