SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5e1cd55958743115fcc906c13069053bea8fb4f39744b5d7860111c0897987a' 
  AND token = '0k4KmJWs/QlZHUI73ImNcXOC48iTwEwzuvM7rJU99WQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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