SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3f5170bebf6eddc3f064303e404dd41e714f244d98d644ba682b0ad38b415ed' 
  AND token = 'uQmfKyuQTXB9ffJjUbRWgdFZQ5VllL6AlG4quUtNpII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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