SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d2bf68198c6d6e2ed811cf78064443dfb22bda642146a6813d0966a304ebe2' 
  AND token = 'uqd8g2anRYicgyBYeCL0ZcL8SqXsaM0OY2ZJtRc39xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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